Brain Teasers – Fall ’22

NOTE:  Newest BTs in red, Bonuses in blue, comments in green, updates in purple.  For reminders on ways to submit answers, see below.

1. Always, sometimes, or never?  A given rectangle is also a square.
2. What’s the second smallest 3-digit palindromic prime?  A) 111 B) 131  C) 313  D)  None of the above  E)  No answer possible.
3. What’s the perimeter of a semicircle of radius pi?
4. A card is drawn from a ‘normal’ deck of playing cards (no jokers).  What’s the probability that the card is either a spade or a face card (J,Q, or K) or both?
5. 
6. The integers 2 and 3 are both primes.  Why are they the only two consecutive integers that are both prime?
7. What are the last two letters in this sequence:  T, N, E, S, S, F, F, T, __, __.
8. What 5-letter English (and British) word has the unique quality that its last four letters are silent?
9. Bonus Trivia:  A)  What was the name of the first artificial satellite launched?  B)  What year was it launched?
10. 
11. Add one mathematical symbol to 55555 to make a statement that equals 500.
12. Which year in the last century read the same upside down and backwards?
13. The Smiths have four daughters.  Each of their daughters has a brother.  What’s the least amount of children the Smiths could have?
14. What occurs twice in a week, once in a year, but never in a day?
15. TRIVIA:  You might know this if you’re a Smothers Brothers fan (or you could google it and who’d know?).  How did the name Fred Hurley and the date 1946 play into a Smothers Brothers routine on their (very old) show?
16. Five couples (10 people) are going on a camping trip for 3 days.  They need to carry their own wather and they read in a guide book that 12.5 liters per day are needed for a party of 5 persons.  How much water should they carry?

Bonus 1:  A circle of radius 1 is inscribed inside the only square that fits.   What’s the area of the part of the square which is NOT in/on the circle?

Bonus 2: See #6 above.  Two primes  that are only two apart (like 5 & 7. 11 & 13, 107 & 109, etc) are called twin primes.  Consider the statement “except for 3 & 5, the number between two twin primes is divisible by 6.”  Is that statement A) always true, B) sometimes true, C) never true, or D) impossible to determine?

Bonus 3:  (See Bonus 2 above, as needed).  One of these statements below is true, one is false, and one is unknown.  Which is which?

A)  The set of primes is infinite.

B)  The set of twin primes is infinite.

C)  The set of ‘trip primes’ (like 3,5,7) is infinite. 

Bonus 4:  See #12 above.  When will that phenomenon happen again? 

Bonus 5:  See #16 above.  If one couple backs out, how much water will they need? 

Brain Teaser solutions may be submitted in several ways:  1) Respond directly to the Mailing e-mail.  2)  Use this Contact form.  3)  Use the Comment section below (soon to be re-instated, if not already.)