MAY 2026 PUZZLE - "Pirate Gold"

Submitted by Dave Thomas

The May Bonus: The Puzzle: There are 5 islands in a row. The Pirate known as the Mandarin Menace has a ton of gold hidden on one of them. During the day you have enough time to sail to just one island to find the gold. But, every night, the pirate moves all that gold exactly one island over. If it was on island 3, it gets moved to either island 2 or 4.

The May Bonus: What is the best strategy for finding the gold? Is it possible to be sure of finding the gold?

Hall of Fame (May Puzzle Solvers):

Mike Arms (NM)
Keith Gilbert (NM)
Harold H. Gaines (KS)

FEBRUARY 2026 PUZZLE - "Area of Inscribed Circlee"

Submitted by Dave Thomas

The February Bonus: What is the area of the inscribed circle in a right triangle with non-hypotenuse sides 5 and 12?

Hall of Fame (February Puzzle Solvers):

Mike Arms (NM)
Rocky S. Stone (NM)
Harold H. Gaines (KS)
Keith Gilbert (NM)

SEPTEMBER 2024 PUZZLE - "Octahedral Dice"

Submitted by Dave Thomas

The September Bonus: What is the expected value for rolling a pair of fair, 8-sided dice?

Hall of Fame (September Puzzle Solvers):

Rocky S. Stone (NM)
Mike Arms (NM)
Earl Dombroski (NM)
K. Sengupta (INDIA)
Keith Gilbert (NM)
Gene Aronson (NM)

AUGUST 2024 PUZZLE - "The Rendezvous"

Submitted by K. Sengupta

Four friends Alfred, Brian, Charles and Derek decided to run around a perfectly circular field which is 1250 metres in circumference.
The respective time taken by Alfred, Brian, Charles and Derek in covering one lap are 10 minutes exactly, 13 minutes 20 seconds, 15 minutes exactly, and 16 minutes 40 seconds.
Alfred and Brian ran in a clockwise direction, while Charles and Derek ran in a counter clockwise direction. Each of the four friends started at the same instant. Alfred, Brian and Charles started from the same point, but Derek started from a point which is 750 metres ahead of Charles in his running direction.

The August Bonus: Determine the time when all the four friends will meet for the first time.

Hall of Fame (September Puzzle Solvers):

Rocky S. Stone (NM)
Mike Arms (NM)

JULY 2024 PUZZLE - "Simultaneous Pie Charts"

Submitted by Dave Thomas

The July Bonus: Evaluate the value (???) of the last Pie.

Hall of Fame (July Puzzle Solvers):

Paul Braterman (UK)
Mike Arms (NM)
Rocky S. Stone (NM)
K. Sengupta (INDIA)

MAY 2024 PUZZLE - "Three to the What?"

Submitted by Dave Thomas

The May Bonus: Evaluate 3⁹⁰⁰ mod 17.

Hall of Fame (May Puzzle Solvers):

Paul Braterman (UK)
Mike Arms (NM)
Earl Dombroski (NM)
K. Sengupta (INDIA)
Kamal Lohia (INDIA)

APRIL 2024 PUZZLE - "That's Some Sum"

Submitted by K. Sengupta

The April Bonus: Solve for AEILMNORS,
where:
AM = sod(NORMA)
dr(MARRY) + dr(MILLIONAIRE) = 15
Note: sod(x) denotes the sum of digits of x and, dr(x) denotes the digital root of x.
sod(12345) = 1+2+3+4+5 = 15,
dr(12345)= 15 = 1+5 = 6.

Hall of Fame (April Puzzle Solvers):

Mike Arms (NM)

BONUS APRIL BONUS - "PRIME PUZZLE"

Submitted by Gene Aronson

PROVE:  f(n, k) = n^k - n is divisible by k for all positive integers n and all prime numbers k.

Hall of Fame (Bonus April Bonus Puzzle Solvers):

Solvers:
K. Sengupta (INDIA)

MARCH 2024 PUZZLE - "It's Diophantine"

Submitted by Dave Thomas

The March Bonus: Solve for x + y + z.
Bonus Bonus: List all positive integer solutions for (x,y,z).

Hall of Fame (March Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
K. Sengupta (INDIA)
Mike Arms (NM)
Gene Aronson (NM)
Harold H. Gaines (KS)
Kamal Lohia (INDIA)

JANUARY 2024 PUZZLE - "Hawks vs Doves"

Submitted by K. Sengupta

The January Bonus: Whenever a hawk meets a dove, the dove is killed. Whenever two hawks meet, they fight to death, and both are killed. And if two doves meet, nothing bad happens.
There are H hawks and D doves, and you are either a hawk or a dove.
Assuming that meetings are random, what are your chances of survival?.

Hall of Fame (January Puzzle Solvers):

The November Bonus: Solve for X.

Hall of Fame (November Puzzle Solvers):

Paul Braterman (UK)
Earl Dombroski (NM)
Rocky S. Stone (NM)
K. Sengupta (INDIA)
Mike Arms (NM)
Eiichi Fukushima (NM)
Keith Gilbert (NM)
Gene Aronson (NM)
Swami Lad (ND)
Harold H. Gaines (KS)

SEPTEMBER 2023 PUZZLE - "Drop Mystery"

Submitted by K. Sengupta

Adam and Beau both have a whole number of chocolate drops, fruit drops and lemon drops, and the product of the number of each boy's of chocolate drops, fruit drops and lemon drops is 336. It is known that:

• Each boy has fewer chocolate drops than fruit drops.
• For each boy, the product of the number of chocolate drops and fruit drops equals the total number of candies he has.
• Adam has more fruit drops than lemon drops

The September Bonus: What is the number of chocolate drops, fruit drops and lemon drops possessed by each of Adam and Beau?

Hall of Fame (September Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Rocky S. Stone (NM)

AUGUST 2023 PUZZLE - "And The Angle Is..."

Submitted by Dave Thomas

Given triangles having two isosceles triangles at their bases, as shown.

The August Bonus: What is Angle X? And what is Angle Y?

Hall of Fame (August Puzzle Solvers):

Earl Dombroski (NM)
Paul Braterman (UK)
K. Sengupta (INDIA)

JUNE 2023 PUZZLE - "Roll Them Bones"

Submitted by K. Sengupta

Alex can see three sides of each of two dice, and he notices that the total number of pips showing is a perfect cube.

The June Bonus: What are the numbers of pips on each face that Alex can see?

Hall of Fame (June Puzzle Solvers):

Rocky S. Stone (NM)
Earl Dombroski (NM)
Gene Aronson (NM)
Mike Arms (NM)

MARCH 2023 PUZZLE - "I'll have a Double Cone"

Submitted by Dave Thomas

In the cone shown above (in two orientations), the shaded portion represents a liquid that has half the volume of the cone.

The March Bonus: If the height of the dry half at left is 6 zarns, how tall is the dry half at right?

Hall of Fame (March Puzzle Solvers):

Paul Braterman (UK)
Earl Dombroski (NM)
Rocky S. Stone (NM)
K. Sengupta (INDIA)
Harold H. Gaines (KS)

DECEMBER 2022 PUZZLE - "Takin’ a Slow Train"

Submitted by K. Sengupta

The cities of Ramonsdale and Stamosville are connected by a railway line whose length in miles is divisible by 264.
A train started from Ramonsdale towards Stamosville and, 6 hours after departing, developed an engine snag which forced it to continue at 5/7 velocity and under an hour late.
If the engine snag had occurred 98 miles later, it would have arrived 24 minutes sooner at its destination.

The December Bonus: How far apart are Ramonsdale and Stamosville? What was the initial speed of the train, and how many minutes late was the train?

Hall of Fame (December Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Gene Aronson (NM)

OCTOBER 2022 PUZZLE - "Uphill Both Ways"

Submitted by Dave Thomas

Jake was late for band practice, because he underestimated the time it would take to ride his bicycle uphill. The uphill trip from Jake's home to the practice house takes 12 minutes longer than the downhill trip back home. Jake's uphill speed is 6 mph, and his downhill speed is 10 mph.

The October Bonus: (A) How far is Jake's home from the practice house? (B) How many minutes would it take Jake to get to practice if the road was flat the whole way?

Hall of Fame (October Puzzle Solvers):

Mike Arms (NM)
K. Sengupta (INDIA)
Paul Braterman (UK)
Rocky S. Stone (NM)
Earl Dombroski (NM)
Harold H. Gaines (KS)
Keith Gilbert (NM)
Gene Aronson (NM)

SEPTEMBER 2022 PUZZLE - "True, False, or Toggle"

Submitted by K. Sengupta

Andre, Bryce, and Cyrek know of a secret 2-digit number. It is known that one of them is a Truthteller, who always tells the truth; one of them is a Liar, who always speaks falsely; and one is an Alternator, who alternates between true and false statements,
Each one of them makes precisely 3 statements regarding the number as follows:

ANDRE:
1. One of the digits is 1.
2. The sum of the digits is 8.
3. Bryce's second statement is false.

BRYCE:
1. One of the digits is 3.
2. The difference of the digits is 4.
3. Precisely one of Cyrek's statement is true.

CYREK:
1. One of the digits is 6.
2. Andre's first statement is false.
3. The first digit is greater in magnitude.

The September Bonus: Determine the secret number from the above-mentioned clues. What are the types of the three men?

Hall of Fame (September Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Mike Arms (NM)
Harold H. Gaines (KS)

AUGUST 2022 PUZZLE - "Pentagonal Ratios"

Submitted by Dave Thomas

Two large pentagons are shown, having the same area, labeled 1 at left. The pentagon at right has an inscribed pentagram (star), revealing a smaller, inverted pentagon, labeled 2.
The August Bonus: (A) What is the ratio of the perimeters of pentagons 1 and 2?
(B) What is the ratio of the areas of pentagons 1 and 2?

Hall of Fame (August Puzzle Solvers):

Earl Dombroski (NM)
Paul Braterman (UK)
Mike Arms (NM)
K. Sengupta (INDIA)
Rocky S. Stone (NM)
Gene Aronson (NM)
Keith Gilbert (NM)
Harold H. Gaines (KS)

JUNE 2022 PUZZLE - "A Cute Angle"

Submitted by Dave Thomas

The June Bonus: A triangle is inscribed in a square as shown. What is angle x?

Hall of Fame (June Puzzle Solvers):

Rocky S. Stone (NM)
Earl Dombroski (NM)
Keith Gilbert (NM)
Gene Aronson (NM)
Swami Lad (ND)

MAY 2022 PUZZLE - "Baser Instincts"

Submitted by Dave Thomas

The May Bonus: In what base is the following equation valid?

Hall of Fame (May Puzzle Solvers):

Keith Gilbert (NM)
Earl Dombroski (NM)
Rocky S. Stone (NM)
Mike Arms (NM)
Gene Aronson (NM)

APRIL 2022 PUZZLE - Celebrate Your Roots"

Submitted by Dave Thomas

The April Bonus: What is the solution to the following? Is there more than one?

Hall of Fame (April Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Mike Arms (NM)
Keith Gilbert (NM)

MARCH 2022 PUZZLE - "A Marriage Ensemble"

Submitted by Dave Thomas

Dan and Terry are two husbands. Their wives are Betty and Julia, not necessarily in that order. The combined ages of the foursome is 106 years. Each husband is 5 years older than his wife. Terry is 4 years younger than Dan. The combined ages of Dan and Betty is 53 years.

The March Bonus: Which husband is married to which wife? How old is each individual?

Rocky S. Stone (NM)
Mike Arms (NM)
Harold H. Gaines (KS)
Earl Dombroski (NM)
Eiichi Fukushima (NM)

FEBRUARY 2022 PUZZLE - "Godzilla Primes"

Submitted by Dave Thomas

The graph above shows the occurrence of various differences between all the prime numbers below 1,000,000. There are only two pairs with a difference of 1 (1,2 and 2,3); many pairs with a difference of 2 (3,5; 5,7; 11,13; etc.); only one pair with a difference of 3 (2,5); and many pairs with differences of 4, 6, 8, and so on. Generally, the odds counts are all less than that for the difference of one. The top graph shows all differences for primes < 100,000(odds and evens), while the middle graph shows even differences only, and the bottom graph, both (red=odds & evens, black=evens).

The February Bonus: The plot of even differences looks like Godzilla's teeth. The differences at the tip of each "tooth" are multiples of a single number. What is that number?

Earl Dombroski (NM)

JANUARY 2022 PUZZLE - "The Timing of Venus"

Submitted by Dave Thomas

The sidereal period of Venus is 225 days, or 0.616 earth years. The most recent Greatest Eastern Elongation (maximum "Evening Star") was on October 29th, 2021. Venus is at inferior conjunction (in front of the Sun) as of press time, January 7th, 2022.

The January Bonus: (A) When will the next Greatest Eastern Elongation of Venus occur? (The time between greatest eastern elongations is called a synodic period.)
(B) What remarkable thing happens in five synodic periods?

Hall of Fame (January Puzzle Solvers):

Earl Dombroski (NM)

DECEMBER 2021 PUZZLE - "Autofilling Teams"

Submitted by Dave Thomas

Players in a weekly football pool choose winners of 15 contests between the 32 NFL teams. The person entering picks in a spreadsheet can use the autofill function to enter teams quickly. If the two opposing teams (in blue) are at the top of a column, only the first letter needs to be typed in most cases. In the 3rd column above, typing a D will fill as DEN, and typing a K will fill as KC.
However, when the opposing teams start with the same letter (like S, for both SF and SEA), the autofill does not work well, and errors (like entering Seattle for someone who actually chose San Francisco) are much more common.
The 32 teams are: ARI, AZ, BAL, BUF, CAR, CHI, CIN, CLE, DAL, DEN, DET, GB, HOU, IND, JAX, KC, LAC, LAR, LV, MIA, MIN, NE, NYG, NYJ, NO, PHI, PIT, SEA, SF, TB, TEN, and WAS.

The December Bonus: (A) For a contest between any random pair of teams, what is the probability that the two teams start with the same letter?
(B) For a weekly schedule of 15 games, what is the probability that n of the 15 will have same-letter teams, where n = 0, 1, 2, and 3?

Hall of Fame (December Puzzle Solvers):

Results for 2021-22 Season:
10 weeks with 0 pairs, 2 with 1, 5 with 2, 1 with 3, and none with higher than 3.

NOVEMBER 2021 PUZZLE - "Mark The Date"

Submitted by Dave Thomas

The November Bonus: What do the following seven dates have in common?

March 14th (π day), June 6th (D Day), July 4th (Independence Day), August 8th (Nixon Resignation Day), September 19th (Talk like a Pirate Day), October 31st (Halloween), and December 26th (Boxing Day).

Hall of Fame (November Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Austin Moede (NM)
Harold H. Gaines (KS)

OCTOBER 2021 PUZZLE - "Office Football Pool"

Submitted by Dave Thomas

Eight staffers at an office participate in a weekly football pool. The pool goes for 16 weeks of the NFL season. The participants are evenly matched as regards predicting game winners. Each week has a definite winner, predictions of the total score for Monday night football are used to break ties.

The October Bonus: What is the most likely number of wins for any given participant over the course of the 16-week season?

Hall of Fame (October Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Keith Gilbert (NM)
Harold H. Gaines (KS)

OCTOBER 2021 PUZZLE - "Office Football Pool"

Submitted by Dave Thomas

Eight staffers at an office participate in a weekly football pool. The pool goes for 16 weeks of the NFL season. The participants are evenly matched as regards predicting game winners. Each week has a definite winner, predictions of the total score for Monday night football are used to break ties.

The October Bonus: What is the most likely number of wins for any given participant over the course of the 16-week season?

Hall of Fame (October Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Keith Gilbert (NM)
Harold H. Gaines (KS)

NOVEMBER 2021 PUZZLE - "Mark The Date"

Submitted by Dave Thomas

The November Bonus: What do the following seven dates have in common?

March 14th (π day), June 6th (D Day), July 4th (Independence Day), August 8th (Nixon Resignation Day), September 19th (Talk like a Pirate Day), October 31st (Halloween), and December 26th (Boxing Day).

Hall of Fame (October Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Austin Moede (NM)
Harold H. Gaines (KS)

OCTOBER 2021 PUZZLE - "Office Football Pool"

Submitted by Dave Thomas

Eight staffers at an office participate in a weekly football pool. The pool goes for 16 weeks of the NFL season. The participants are evenly matched as regards predicting game winners. Each week has a definite winner, predictions of the total score for Monday night football are used to break ties.

The October Bonus: What is the most likely number of wins for any given participant over the course of the 16-week season?

Hall of Fame (October Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Keith Gilbert (NM)
Harold H. Gaines (KS)

SEPTEMBER 2021 PUZZLE - "Multiple Choice"

Submitted by Dave Thomas

(1) If you choose an answer to this question at random, what is the chance you will be correct?

(2) If you choose an answer to this question at random, what is the chance you will be correct?

Hall of Fame (September Puzzle Solvers):

Rocky S. Stone (NM)
Earl Dombroski (NM)
Mike Arms (NM)

AUGUST 2021 PUZZLE - "G-Whiz Legislation"

Submitted by Dave Thomas

An amendment to a huge omnibus spending bill, submitted by Rep. Louie Gohmert (R-Texas), was adopted when the bill passed both houses, and was promptly signed into law by President Biden. The bill came to 15,427 pages in length. It seems few noticed the obscure amendment, lurking inside a section on COVID relief for Antarctic penguins. The amendment reads “As a means to mitigate climate change, the value of The Universal Constant, G, is hereby mandated to be reduced by 5%, to 6.340376x10^-11 m³ kg^-1 s^-2, at the stroke of midnight on December 21st, 2021.” Surprisingly, God (he/him/his), who is notorious for being indifferent to prayer, was moved to enact this particular mandate. Aides were rumored to have heard the Lord mumbling to himself “Hoo boy, this gonna be good.” And so, at midnight on the Solstice, the value of G was instantaneously reduced by 5%.

The August Bonus:What happened? Did the earth’s orbital radius increase, or decrease? And by how much? [Note: this is a seriously difficult problem, and conjectures about the general solution are welcomed.]

Hall of Fame (August Puzzle Solvers):

Earl Dombroski (NM)

JULY 2021 PUZZLE - "A Liar in the Family"

Submitted by Dave Thomas

A prominent political family became entangled in a tax fraud scheme. Four members of the family were deposed together, and their dysfunctional, alcoholic lawyer told each one to give only two statements at the deposition: one true, and one false. The family took this advice to heart, and each gave their two statements accordingly.
Melania said "I didn't cheat! It was Eric."
Don Jr. said "Melania cheated. It wasn't Eric."
Eric said "It wasn't Don Jr. It wasn't Ivanka."
And Ivanka said "It wasn't Eric. The cheater was me!"

The July Bonus:Who is the cheater?

Hall of Fame (July Puzzle Solvers):

Mike Arms (NM)
Earl Dombroski (NM)
Rocky S. Stone (NM)
Keith Gilbert (NM)
Gene Aronson (NM)
Harold H. Gaines (KS)
Austin Moede (NM)

JUNE 2021 PUZZLE - "The Fauci Ouchie"

Submitted by Dave Thomas

A director of a small firm (less than 50 employees) made the following announcement: "Several staff have asked me how we're doing on the vaccine front. We're at 87.2% fully vaccinated."

The June Bonus:How many staff members are fully vaccinated? And how many are not fully vaccinated?

Hall of Fame (June Puzzle Solvers):

Mike Arms (NM)
Earl Dombroski (NM)
Harold H. Gaines (KS)
Paul Braterman (UK)

MAY 2021 PUZZLE - "Pirate Treasure"

Submitted by Dave Thomas

You have been captured by Pirates while sailing the Carribean, and have been brought before their gruff Captain. With a sinister snarl, he barks "I've a chest here that holds 120 pounds of pure gold coins. Some of these coins be decloons [10 Troy ounces each], and the rest be triploons [three Troy ounces each]. Now, mate, if ye can tell me exactly how many decloons and triploons are in my chest, ye walks away a free man. Get it wrong, and ye'll be walkin' the Plank!" After another pirate suggested that the riddle was perhaps overly challenging, the Captain snorted, and then offered a hint: "Awright, matey - the number of decloons times the number of triploons couldn't be larger!"

The May Bonus:For your life - how many decloons and how many triploons are in the chest?

Hall of Fame (May Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Paul Braterman (UK)
Gene Aronson (NM)
Keith Gilbert (NM)
Allen Robnett (NM)

APRIL 2021 PUZZLE - "Herd Immunity"

Submitted by Dave Thomas

If a new disease-causing virus comes along with a “spread factor” R₀ of one new infection per infected individual, a possible pandemic will fizzle out, with no need for mass vaccination. For R₀ = 10 new infections per each infected person, however, about 90% of the population will need to be vaccinated to prevent a new pandemic.

The April Bonus:If the novel coronavirus of 2019 has an R₀ of 3, what percent of the population should be vaccinated to prevent a new pandemic?

Hall of Fame (April Puzzle Solvers):

Earl Dombroski (NM)
Paul Braterman (UK)
Keith Gilbert (NM)

MARCH 2021 PUZZLE - "Roll Up Your Sleeve"

Submitted by Dave Thomas

Three nurses, Kim, Frank and Mary, can together administer three times the number of vaccines per hour as Mary alone, and four times the number of vaccines as Frank alone.

The March Bonus:If the slowest nurse can perform six vaccines per hour, how many people can the team of three nurses inoculate in one hour?

Hall of Fame (March Puzzle Solvers):

Earl Dombroski (NM)
Keith Gilbert (NM)
Mike Arms (NM)
Paul Braterman (UK)
Gene Aronson (NM)
Allen Robnett (NM)
Terry Lauritsen (NM)
Harold H. Gaines (KS)

FEBRUARY 2021 PUZZLE - "Arms Spread Wide"

Submitted by Dave Thomas

At 6:00 AM and 6:00 PM, a clock's hour and minute hands are exactly 180 degrees apart.

The February Bonus:How many times does this opposition occur in a single day? What are those times?

Hall of Fame (February Puzzle Solvers):

Earl Dombroski (NM)
Gene Aronson (NM)
Terry Lauritsen (NM)
Rocky S. Stone (NM)

JANUARY 2021 PUZZLE - "Rollin’ on the River"

Submitted by Dave Thomas

A rowing enthusiast can propel a boat at 4km/hr in still water. The rower takes the boat 7 km upstream, and then 7 km downstream, returning to the starting point after 8 wearying hours.

The January Bonus:How fast is the stream flowing?

Hall of Fame (January Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Keith Gilbert (NM)
Paul Braterman (UK)
Gene Aronson (NM)
Terry Lauritsen (NM)

DECEMBER 2020 PUZZLE - "A π and 5 Surprise"

Submitted by Ben Sparks / Numberphile

Consider a small number x that is 1 over n 5s; for example, if n = 3, the number x is 1/555.

The December Bonus:Show that the sine of x, evaluated in degrees, is approximately sin_d(x) = π / 10²⁺ⁿ.

Extra Bonus: Show that the result becomes more accurate as n is increased: [10²⁺ⁿ sin_d(x) – π ] ≈ π / 10ⁿ

Hall of Fame (December Puzzle Solvers):

Earl Dombroski (NM)

NOVEMBER 2020 PUZZLE - "How Far the Moon"

Submitted by Dave Thomas

As this diagram shows, a person viewing the full moon at midnight sees the moon slightly larger than if it was viewed just after rising (dawn) or just before setting (dusk). This is because the moon over the horizon is about the radius of the earth farther from the viewer than is the overhead full moon at midnight.

The November Bonus:Two images of the full moon (one taken at midnight, one at dusk) have been obtained from a digital camera, with the exact same focal length and zoom settings.

If the diameter of the digital image of the full moon at midnight is 2536 pixels, and that of the moon at dusk is 40 pixels smaller, what is the distance to the moon, as a multiple of the radius of the Earth, R_E? How does this compare to the actual value? (There is some inaccuracy in measuring diameters from the photos). [Based on a true story.]

Hall of Fame (November Puzzle Solvers):

Earl Dombroski (NM)
Keith Gilbert (NM)

OCTOBER 2020 PUZZLE - "Social Voting"

Submitted by Dave Thomas

Consider the following statistics about Harris County, Texas (includes Houston) and New York County, New York (Manhattan):

The October Bonus:If all of the registered voters in each county formed a line at their polling place, and each voter kept a social distance of six feet from adjacent voters, how long would the typical line be, in miles, in Manhattan? And in Harris County? Assume an equal number of registered Manhattan voters resides in each of the areas for the 250 polling places.

Double Bonus: If a Federal judge grants an injunction barring enforcement of Gov. Abbott's order limiting Texas counties to one ballot dropoff, and twelve ballot centers can be used in Harris County, and are equally distributed, how long would the typical line be, then?

Hall of Fame (October Puzzle Solvers):

Earl Dombroski (NM)
Rocky S. Stone (NM)
Mike Arms (NM)
Allen Robnett (NM)

SEPTEMBER 2020 PUZZLE - "Weaning Weekly!"

Submitted by Dave Thomas

The September Bonus:A patient has been instructed to wean themselves off of a daily medication. Here is the schedule the doctor has recommended:

• Week 1 - one pill per day as usual
• Week 2 - one pill every other day
• Week 3 - one pill every 3rd day
• Week 4 - one pill every 4th day
• Week 5 - one pill every 5th day
• Week 6 - one pill every 6th day
• Week 7 - stop pills altogether

The September Bonus:Starting with Sunday, the first day of Week 1, how many pills will the patient need to get to Week 7?

Hall of Fame (September Puzzle Solvers):

Rocky S. Stone (NM)
Mike Arms (NM)
Gene Aronson (NM)
Terry Lauritsen (NM)
Keith Gilbert (NM)

AUGUST 2020 PUZZLE - "Bazinga!"

Submitted by Dave Thomas

The August Bonus:Solve for ??

Hall of Fame (August Puzzle Solvers):
Paul Braterman (UK)
Mike Arms (NM)
Rocky S. Stone (NM)
Keith Gilbert (NM)
Terry Lauritsen (NM)
Gene Aronson (NM)

JULY 2020 PUZZLE - "Multiple Protection"

Submitted by Dave Thomas

The July Bonus:

• If a bandana is 60% effective in preventing transmission of the coronavirus, and a paper face mask is 80% effective, how effective is the combination (mask and bandana together)?
• If a bandana provides 40% probability of allowing transmission of the coronavirus, and a paper face mask provides 20% probability, what is the probability of allowing transmission for the combination (mask and bandana together)?
• What is the mathematical relationship of the two answers (A) and (B)?

Hall of Fame (July Puzzle Solvers):
Mike Arms (NM)
Paul Braterman (UK)
Keith Gilbert (NM)
Rocky S. Stone (NM)
Terry Lauritsen (NM)

JUNE 2020 PUZZLE - "Picture-Perfect Puzzle"

Submitted by Dave Thomas

The June Bonus:What is the Answer ??

Hall of Fame (June Puzzle Solvers):

MAY 2020 PUZZLE - "Corona EMT Blues"

Submitted by Dave Thomas

An emergency medical technician has to transport three individuals from a public testing site to a waiting area at the hospital. One of the three, Steve, has never been exposed to the coronavirus Covid19, and is Susceptible to getting the disease. A second person, Cathy, is Contagious with Covid19. The third person, Rachel, has contracted and Recovered from Covid19, but may still be contagious.
The medic can only transport one patient at a time. They can’t leave the susceptible person and the contagious person together in either location, because if the EMT isn’t there to enforce social distancing, the susceptible person could become infected. Likewise, they can’t leave the susceptible person and the recovered person together in either location, because the recovered patient might still be contagious.

The May Bonus:How can the medic safely transport the three patients to the waiting area of the hospital, while maintaining social distancing?

Hall of Fame (May Puzzle Solvers):

APRIL 2020 PUZZLE - "Train's a-Comin'!"

Suggested by Rocky Stone, from "The 125 Best Brain Teasers of All Time - by Marcel Danesi"

A train leaves New York for Washington every hour on the hour. Similarly, a train leaves Washington for New York every hour on the half-hour. The trip takes five hours each way.

The April Bonus:If you are on the train from New York bound for Washington, how many of the trains coming from Washington going toward New York would you pass?

Hall of Fame (April Puzzle Solvers):

Allen Robnett (NM)
Paul Braterman (UK)
Terry Lauritsen (NM)

MARCH 2020 PUZZLE - "Ready, Aim, Fire!"

Submitted by Dave Thomas

A cannon is being used in an artillery exercise to shoot a target some distance away. The cannon is tilted at the maximum-range angle of 45^o; assume gravitational acceleration is g=10m/sec².

In the first attempt, the muzzle velocity was set at 110 m/sec, but the target was over-shot by 210 meters.

The March Bonus:

• What value should the muzzle velocity be set at to hit the target?
• If muzzle velocity is not changed, what angle(s) should the cannon be tilted at to hit the target?

Hall of Fame (March Puzzle Solvers):

Paul Braterman (UK)
Keith Gilbert (NM)
Gene Aronson (NM)

FEBRUARY 2020 PUZZLE - "Measuring a Mast"

Submitted by Dave Thomas

South of Belen, a radio mast can be found near I-25, a short distance to the east of the freeway. The angular size of the mast, measured from the north-bound lane of I-25, is about 22^o. The same angle, measured from the south-bound lane, is about 18^o. The two lanes are 36 meters apart.

The February Bonus:

• How tall is the mast (H)?
• How far is the mast from the north-bound lane (X)?

Hall of Fame (February Puzzle Solvers):

Rocky S. Stone (NM)
Eiichi Fukushima (NM)
Keith Gilbert (NM)
Allen Robnett (NM)
Harold H. Gaines (KS)
Swami Lad (ND)
Gene Aronson (NM)

JANUARY 2020 PUZZLE - "Wasting Away"

Submitted by Dave Thomas

A certain radioactive element, Unobtanium, loses one percent of its mass in a year.

The January Bonus:What is Unobtanium’s half-life?

Hall of Fame (January Puzzle Solvers):

Paul Braterman (UK)
Keith Gilbert (NM)
Rocky S. Stone (NM)
Gene Aronson (NM)
Harold H. Gaines (KS)

DECEMBER 2019 PUZZLE - "Fantastic Football Picks"

Submitted by Dave Thomas

Alissa and Greg are participating in an office NFL pool. This week, with 14 of 16 games played so far, they are tied for first place, with 12 correct picks each. For the remaining two games in the week, Greg and Alissa have chosen different teams for both games.

The December Bonus:(A) What is the probability that Greg and Alissa will be tied at week's end?
(B) If there were four games remaining, and Alissa and Greg picked different teams for all four, what is the probability that Greg and Alissa will be tied at week's end?
(Extra Credit) If there were n games remaining (n = any positive even number), and Alissa and Greg picked different teams for all n, what is the probability that Greg and Alissa will be tied at week's end? (Assume that overtimes will be used until a clear winner emerges for each football game; no ties allowed.)

Hall of Fame (December Puzzle Solvers):

Keith Gilbert (NM)
Paul Braterman (UK)

NOVEMBER 2019 PUZZLE - "Vive la Resistance"

Submitted by Dave Thomas

The November Bonus:if the resistances R in the circuit above all equal 15 ohms, what is the resistance between contacts A and B?

Hall of Fame (November Puzzle Solvers):

Eiichi Fukushima (NM)
Harold H. Gaines (KS)
Allen Robnett (NM)
Keith Gilbert (NM)
Gene Aronson (NM)

OCTOBER 2019 PUZZLE - "Pretty Prime Powers"

Submitted by Dave Thomas

The October Bonus:The October Bonus is a variation on September’s theme:

Solve for X, in 3^X = X⁷.

Hall of Fame (October Puzzle Solvers):

Gene Aronson (NM) Mike Arms (NM)
Harold H. Gaines (KS)

SEPTEMBER 2019 PUZZLE - "Three Ring Circle"

Submitted by Dave Thomas

The September Bonus:

Solve for X, in 3^X = X³.

Hall of Fame (September Puzzle Solvers):

Gene Aronson (NM)
Paul Braterman (UK)
Mike Arms (NM)
Harold H. Gaines (KS)
Zsolt Nagy (Germany)

AUGUST 2019 PUZZLE - "Pricy Trash Run"

Submitted by Dave Thomas

Suppose you have a rocketload of undesirable trash (perhaps radioactive sludge, or vain politicians’ tweets), and you’ve managed to get it off Earth, and into an Earth-like circular orbit (radius R ~ 1.5x10^11 meters, orbital speed ~ 30,000 meters/second ~ √(GM/R)). Now, you want to dump the trash barge right into the Sun.

The August Bonus:
Of the two methods outlined below, which is the most economical approach? Also, estimate how many joules per kilogram of barge will be required for both methods?

(A) Fire the trash barge’s rockets in the opposite direction of its orbit around the Sun, bringing it to a standstill, from which it would plummet directly into the sun. (This is the inner orbit shown above.)

(B) Briefly fire the barge's rockets in the same direction of motion as the rocket, giving it an elliptical orbit with the perihelion near Earth’s orbital radius, and an aphelion near Jupiter's orbital radius (~7.8x10^11 meters). Once the barge reaches aphelion, then fire the rockets in the opposite direction of its orbit around the Sun, bringing it to a standstill, whereupon it will plunge into the Sun. (This is the outer orbit above.)

Note: assume both Earth and Jupiter are considered "elsewhere" in the solar system for the entire duration, and are shown for scale only. They will not affect the barge in its orbit around the sun. In other words, sun and barge are a 2-body problem.

Hall of Fame (August Puzzle Solvers):

Earl Dombroski (NM)

JULY 2019 PUZZLE - "Takes a Licking, Keeps on Ticking..."

Submitted by Dave Thomas

Suppose you could take an Earthly pendulum clock, of pendulum length L = one meter, to (A) the Moon’s surface, or to (B) Jupiter’s surface. Use the figures below to calculate gravitational acceleration on the surfaces of the Earth, the Moon, and Jupiter.

The July Bonus:
How slow or fast would the clock run on the Moon and on Jupiter, compared to Earth?

Hall of Fame (July Puzzle Solvers):

Allen Robnett (NM)
Earl Dombroski (NM)
Keith Gilbert (NM)
Gene Aronson (NM)
Harold H. Gaines (KS)

JUNE 2019 PUZZLE - "Date with Death"

Submitted by Dave Thomas

Our hero, Dr. Normal, must face seven deadly challenges in order to defeat the arch-villain Tweeter-Man. He only has one chance in seven of surviving each challenge.

The June Bonus:
What is the probability that Dr. Normal will die during the ordeal?

Hall of Fame (June Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Keith Gilbert (NM)
Allen Robnett (NM)
Harold H. Gaines (KS)

MAY 2019 PUZZLE - "Three of a Kind"

Submitted by Dave Thomas

The probability of getting three of a kind in 5-card draw poker (52 cards, 4 suits, 13 ranks per suit) is just over 1 in 50.

The May Bonus:
What is the probability of getting three of a kind in 6-card draw poker? Is it more or less than that for 5-card draw?

Hall of Fame (May Puzzle Solvers):

Earl Dombroski (NM)
Keith Gilbert (NM)
Allen Robnett (NM)
Mike Arms (NM)

APRIL 2019 PUZZLE - "Co-ed Debates"

Submitted by Dave Thomas

In the primary election, nine male and seven female candidates are running for president. Rather than have all 16 candidates try to debate at once, the League of Human Voters has decided to hold four debates, with just four candidates in each event. The debate panel foursomes are to be chosen randomly.

The April Bonus:
How much more likely is a balanced panel (two male/two female) than an all-male panel? And how much more likely is an all-male panel than an all-female panel? (Ratio of probabilities for both.)

Hall of Fame (April Puzzle Solvers):

Earl Dombroski (NM)
Allen Robnett (NM)
Mike Arms (NM)

MARCH 2019 PUZZLE - "Running the Bases"

Submitted by Dave Thomas

The March Bonus:
In what base is the equation 2383 + 2473 + 2601 + 2680 = 11357 valid?
And what is the sum, in Base 10?

Hall of Fame (March Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Allen Robnett (NM)
Keith Gilbert (NM)

FEBRUARY 2019 PUZZLE - "Fishy Encounter"

Submitted by Dave Thomas

A fish whose eyes are one meter below the surface of a river spots a boy. The boy's eyes are one meter above the surface. The horizontal distance between the boy and the fish is two meters. The index of refraction of air is n₁ = 1, and that of water is n₂ = 4/3.

The February Bonus: What are the angles of incidence (I) and refraction (R)?

Hall of Fame (February Puzzle Solvers):

Earl Dombroski (NM)
Gene Aronson (NM)
Allen Robnett (NM)
John Geohegan (NM)
Keith Gilbert (NM)

JANUARY 2019 PUZZLE - "Clock Palindromes"

Submitted by Dave Thomas

Sometimes the time of day, in hours:minutes:seconds, can be a palindrome. Examples of such palindromes include 5:29:25 and 10:33:01.

The January Bonus:

• Of the 86,400 seconds of a day, how many are palindromes?
• What is the shortest interval between two palindromes?
• How many palindromes come five minutes after their predecessors?

Hall of Fame (January Puzzle Solvers):

Earl Dombroski (NM)
Mike Arms (NM)
Rocky S. Stone (NM)
Gene Aronson (NM)

Check out the Old Puzzle Archive, HERE!

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