Solve this Problem coin flipping?

Question

You are in a dark room. There is a table on which there are 50 coins (18 heads and 32 tails). There is no way you can tell (by seeing, touching etc.,) whether a coin is head or tail.

You have to somehow seperate the coins in to 2 groups so that each group has same number of heads. You can flip any coins you want.

Answer 1

gjmb1960 is assuming that the two groups (the 18 and the 32) are separated. I don't think that's what the problem-writer meant.

Here's the solution:
Count out (in the dark) 18 coins. This is one of the 2 groups you have to create. Let's say that it has x heads.
Then the other group has to have the rest of the heads, which would mean it has 18 - x heads.

But if you simply reverse (flip) all of the 18 coins you selected, the x heads will become tails, and the remaining 18 - x tails will become heads. And that's exactly the number of heads in the other group of coins: 18 - x.

Summary: All you have to do (in the dark) is count out a group of 18 coins and flip them over.

Answer 2

Well, I have best guess. It depends on the type of coin. THe side with the more decoration stuff. THe side with more is more heavy, therefore more probable in a coin toss. I'd just flip all the coins a couple times and put them in the same pile.

Answer 3

take the biggest group , you can find it by counting in the dark.
from this group flip 18 coins and voila two groups of 18 heads

Answer 4

you're so totally wrong acutaor. what if you had 17 heads and 1 tail? pick 19 so you have 31 and 19. The 19 group has at least one tails, at most 19. The 31 group has at most 31 tails, at least 13. If you pick 19 from the 31 you have at least one tails, at most 19, with 12 left over. So now you have two groups of 19 and one of 12. Wow i don't know.

Answer 5

Do you have a cell phone? Use the light emitted from the screen of your cell phone to look at the coins. Simple!

Answer 6

Turn the light on