Sandy Wood
Brain Game: 5 Coins in a Pool
by Sandy Wood - February 13, 2009 - 7:30 AM

bloghead_braingames.jpg

I’m eager to hear your thoughts on today’s puzzle, since it mixes a bit of math with a logic puzzle and some deductive reasoning. The puzzle may be tough, but it’s clearly solvable. It just takes a close examination of the given information and the possibilities rendered. Here we go; good luck!

Five siblings – Barry, Carrie, Harry, Larry, and Mary – were learning how to swim. Once they became good enough to swim to the bottom of the pool and back up, the kids’ father used to toss coins in the pool. They’d sink to the bottom, and the youngsters would dive down to retrieve them.

On one such instance, the dad looked into his pocket. He had five coins totalling 91 cents, and he threw all five of them into the pool. The kids dove in, and each rose to the surface with one of the five coins. Based on the following two clues, can you determine which child retrieved which coin?

1. Harry’s coin was worth
one-fifth as much as Mary’s coin.

2. Carrie’s coin was worth
ten times as much as Barry’s coin.

Here is the SOLUTION.

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Comments (20)

  1. Larry had a 50 c coin, Mary a quarter, Carrie a dime, Harry a nickel and Barry a penny…am I right?

    posted by sandie on 2-13-2009 at 7:45 am

  2. Good quiz! I was staring at completed grids of barry=1 and barry=5 and couldn’t sort it out. I didn’t realize I was violating the rules on the barry=5 chart until I read the answer. Then I was all duh and stuff.

    posted by Reed on 2-13-2009 at 8:18 am

  3. That wasn’t difficult at all…..

    posted by Lisa on 2-13-2009 at 8:30 am

  4. agreed….I got it pretty fast

    posted by Ian on 2-13-2009 at 8:35 am

  5. You’re absolutely right, Sandie. Nice job!

    posted by Sandy Wood on 2-13-2009 at 8:37 am

  6. same here – got it pretty fast, but I do a lot of those gridded logic puzzles, so I’ve kind of been in training for this.

    posted by Diana on 2-13-2009 at 8:41 am

  7. this was a fun one! a bit easy though.

    posted by jp on 2-13-2009 at 9:50 am

  8. Heh — I wish they were as easy to devise as they seem to be to solve!

    posted by Sandy Wood on 2-13-2009 at 10:23 am

  9. I thought that quiz was easy but to make it interesting I used Excel’s Solver. Made the two rules into equations = 0 and let excel solve the puzzle. Took me about 10 times longer doing this than acutally solving the puzzle by hand but it got the right answers.

    posted by GBurns on 2-13-2009 at 10:58 am

  10. I had some trouble originally until I realized you were including 50-cent pieces, since I couldn’t work out the 91 cents using precisely five regular coins. 50 cent coins are basically non-existent in Canada, so I hadn’t included them in my original list.

    posted by Jacquilynne on 2-13-2009 at 11:46 am

  11. I didn’t see that each coin was used only once. I have:
    B=nickel
    C=half dollar
    H=penny
    L=quarter
    M=nickel

    Am I wrong with my math?

    posted by Tim on 2-13-2009 at 12:24 pm

  12. I got:
    B=nickel
    C=half dollar
    H=penny
    L=quarter
    m=nickel
    Were we only allowed to use each coin once or is my math wrong?

    posted by Tim on 2-13-2009 at 12:26 pm

  13. All coins need to add up to $0.91

    posted by GBurns on 2-13-2009 at 12:37 pm

  14. Tim, the puzzle didn’t say that the coins had to be all different… but it did specify that the total of the five coins was 91 cents. The only way to get that is with a half-dollar, quarter, dime, nickel, and penny. Your combination only totals 86 cents.

    posted by Sandy Wood on 2-13-2009 at 12:39 pm

  15. h = 5
    m = 25
    c = 10
    b = 1
    l = 50
    Nice!

    posted by wit of a twit on 2-13-2009 at 2:03 pm

  16. Fun! I got that right away–I wrote M=5H and knew Mary had to have a quarter. The rest was easy after that! Thanks for the great puzzle! :)

    posted by Orange on 2-13-2009 at 4:23 pm

  17. well that wasn’t hard, got in in 10 seconds.

    posted by Tobias on 2-13-2009 at 7:01 pm

  18. Sandy wrote “I wish they were as easy to devise as they seem to be to solve!”
    Maybe that should be the new puzzle to devise a puzzle?
    They are a good but harder to put together than to solve most of the time.

    posted by Kev in GA on 2-13-2009 at 7:08 pm

  19. Who carries a half dollar around in their pocket??? So what that the question wouldn’t make sense without it…but seriously, who does that?!?

    posted by bevr_retrvr on 2-14-2009 at 1:11 am

  20. 50 L
    25 M
    10 C
    5 H
    1 B

    too easy

    posted by ir_kr on 2-15-2009 at 12:26 pm

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