Larry Campbell Brain Teasers

Summary & Solutions: Mar/Apr ’23 BTs

REMINDERS:  Answers in red.  Solvers (submitted/correct) in blue. (Forgive any omissions, but feel free to inform.) Comments in green. For further elaboration on solutions, please feel free to ask! 

Submitters of at least one correct solution:  Rita Barger, Amy Ragsdale, Anita Dixon, Kurt Killion

  1. Mary’s mother had three daughters. The first two were named April and May.  What was the name of the third daughter? Mary! 🙂  Rita Barger, Amy Ragsdale, Anita Dixon
  2. A cheetah was clocked running 550 feet in 10 seconds. About how many miles per hour is that? 37.5 Rita Barger, Amy Ragsdale, Anita Dixon
  3. Ninety six is 37.5% of what number? 256 Rita Barger, Amy Ragsdale, Anita Dixon
  4. What is the mean and the median of the first 12 prime numbers? mean = 16.42 (nearest tenth). Median = 16 Rita Barger, Amy Ragsdale, Anita Dixon
  5. True or False?  Every two-digit composite (non-prime) number is even.  False. (15, e.g.) Rita Barger, Amy Ragsdale, Anita Dixon
  6. You have 3 dice – one red, one blue, one white, and you roll them.  a) how many different outcomes are possible? 216. Anita Dixon  b) What are the possible sums of those rolls? (NOTE.  This is a change from an earlier wording.) Sums from 3 to 18, inclusive, are possible. (Though not all are equally likely.) Rita Barger,  Anita Dixon
  7. What are the next three numbers in this sequence?  1, 3, 6, 10, 15, _21__, _28__, _36__ Rita Barger, Amy Ragsdale, Anita Dixon
  8. Why could the word SMILES be considered the longest word in the English language? 🙂 There is a ‘mile’ between the first and last letters. Rita Barger, Amy Ragsdale, Anita Dixon
  9. How is the surface area of a cube affected if the length of each side is doubled? It is four times as large. Rita Barger, Amy Ragsdale, Anita Dixon
  10. How many blocks are in this tower?  —> 9 Rita Barger, Amy Ragsdale, Anita Dixon 3D shapes brain teaser for kids
  11. Would it be cheaper (or the same?) to take one friend to the movies twice, or two friends at the same time? Two friends at once (only 3 admissions instead of 4) Rita Barger, Amy Ragsdale, Anita Dixon
  12. Using each of the digits from 0 to 9 once each, find the two-addend arithmetic addition problem which produces the smallest sum.  (Note the purple update.  Earlier pre-update correct answers have been accepted.) Variety of answers accepted.  One good one: 13579 + 20468.  Rita Barger,  Anita Dixon
  13. Stopping after this BT, we currently have 13 BTs – an unlucky number. 🙁  We’ll ‘fix’ that next Mailing, but if you could eliminate ONE of the BTs right now, which would it be, and why? (Pure opinion – all answers ‘correct’!) Almost anything ‘correct’.  Rita Barger, Amy Ragsdale, Anita Dixon
  14. I’ve seen similar riddles before . . . I think I know ‘the answer’ (logically), but . . .?  Anxious to see other solutions.  (Creative [non-logic?] answers encouraged and probably accepted.) An answer similar to “you will hang me” produces an unavoidable conflict for any outcome.  Rita Barger, Anita Dixon
  15. Fill in the next two entries in this sequence:  F28, M31, A30, M31, _J30__, _J31__ Rita Barger, Amy Ragsdale, Anita Dixon
  16. In what calendar years do Christmas and New Year’s Day fall on the same day of the week?  It never happens!  (Note that it always happens in each calendar SEASON, but never in the same calendar year. 🙂 )  Amy Ragsdale, Anita Dixon
  17. Which whole number has more factors – 60 or 72?  (Verification with numbers expected.) They each have twelve factors. Rita Barger, Amy Ragsdale, Anita Dixon
  18.  Maggie lives on a street with 10 houses. The houses are numbered 1 to 10. If Maggie adds up all the house numbers that are lower than hers, the total is three times her actual house number. What number is Maggie’s house? Number 7. Rita Barger, Anita Dixon
  19. When Ashley was 15, her mother was 37. Now, her mother is twice her age. How old is Ashley? She is now 22 (and her mom is 44). Rita Barger, Amy Ragsdale,  Anita Dixon
  20. The water level in a reservoir is low, but doubles every day. It takes 60 days to fill the reservoir. How long does it take for the reservoir to become half full? 59 days. Rita Barger, Amy Ragsdale, Anita Dixon
  21. Four cars come to a four-way stop, all coming from a different direction. They can’t decide who got there first, so they all proceed at the same time. They do not crash into each other, but all four cars go. How is this possible? Each car is turning right. Anita Dixon, Amy Ragsdale

BONUS 1:  If two dice are rolled, how many of the resulting outcomes have a sum that is divisible by 3?  12.

BONUS 2: See #9 above.  How is the surface area affected if each side is increased by a factor of x ? The surface area grows by a factor of x^2. Rita Barger,  Anita Dixon

BONUS 3:  See #12 above.  Same conditions, same challenge, only for both PRODUCT and DIFFERENCE. Several accepted.  Rita Barger, Amy Ragsdale (partial), Anita Dixon

BONUS 4:  Can you find three consecutive integers such that their sum equals 6 times the middle integer?  -1, 0, 1.  Rita Barger, Amy Ragsdale, Anita Dixon, Kurt Killion