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Solve the problem... win the prize!

Do you like logic problems?

First to solve the following problem and post here the correct answer will be the winner. I'll accept the new set (Pumpkin Eve 3) from him/her.

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The Monkey and the Coconut

Ten people land on a deserted island. There they find lots of coconuts and a monkey. During their first day they gather coconuts and put them all in a community pile. After working all day they decide to sleep and divide them into ten equal piles the next morning.

That night one castaway wakes up hungry and decides to take his share early. After dividing up the coconuts he finds he is one coconut short of ten equal piles. He also notices the monkey holding one more coconut. So he tries to take the monkey's coconut to have a total evenly divisible by 10. However when he tries to take it the monkey conks him on the head with it and kills him.

Later another castaway wakes up hungry and decides to take his share early. On the way to the coconuts he finds the body of the first castaway, which pleases him because he will now be entitled to 1/9 of the total pile. After dividing them up into nine piles he is again one coconut short and tries to take the monkey's slightly bloodied coconut. The monkey conks the second man on the head and kills him.

One by one each of the remaining castaways goes through the same process, until the 10th person to wake up gets the entire pile for himself. What is the smallest number of possible coconuts in the pile, not counting the monkeys?

Posted by jsfreire on Oct 05, 2007 in Swap Meet | 28 comments

jflint on Oct 05, 2007

15

jsfreire on Oct 05, 2007

Nope

DinoBoff on Oct 05, 2007

0

jsfreire on Oct 05, 2007

Nope

aemcg on Oct 05, 2007

10

Coyote on Oct 05, 2007

99

Candee on Oct 05, 2007

89

dustybunny on Oct 05, 2007

79

jsfreire on Oct 05, 2007

Still trying...

jflint on Oct 05, 2007

2519

bdelisio on Oct 05, 2007

359

dustybunny on Oct 05, 2007

839

stacye on Oct 05, 2007

I'm still learning linear algebra. Your diophantine equation foo will not work on me.

bdelisio on Oct 05, 2007

9!=362880

jflint on Oct 05, 2007

10!=3628800

bdelisio on Oct 05, 2007

9!-1 = 362879

jflint on Oct 05, 2007

LCM(1,2,3,4,5,6,7,8,9,10)-1 = 7*2*2*2*3*3*5-1 = 2519

JSun on Oct 05, 2007

3121

dustybunny on Oct 05, 2007

209

redhedinsanity on Oct 05, 2007

3628799

kitt Vip-micro on Oct 05, 2007

Can't be 3121. 3121 % 10 != 9.

soprano on Oct 05, 2007

jflint is right, it's 2519. (I got it without a calculator or pen/pencil or any other tools – just used my brain. :P)

jugglars on Oct 05, 2007

I agree with jflint. 2519 is the right solution. The least common multiple of the number of castaways (10), i.e. the number that would pile up properly for each number of castaways between 1 and 10 is 2520. But the monkey already took one coconut ... 2519

bdelisio on Oct 05, 2007

jflint is right, its the LCM-1.

maldenjen on Oct 05, 2007

1259

jsfreire on Oct 05, 2007

jflint is the winner!

Congrats man... I'll accept the new Pumpkin set from you.

soprano on Oct 05, 2007

Oh wait. I just realized. The answer is -1, isn't it?

JBVisions on Oct 05, 2007

And he's pleased he's got 2519 coconuts to eat! Yeeeuk, I'd be making a fishing rod.