Denman
October 18, 2005, 11:00am
1
There is a room
In the room are 50 coins
18 of them are showing tails
The rest are showing heads.

In the dark without being able to tell which way up the coins are
Sort then in to two groups
With the same amount of heads showing in each group.

answers on a post

I think you grab 25 coins and flip over 7 of them

have to work this out

RogerR
October 18, 2005, 12:20pm
3
actually, i think it might be the other way around; grab 25, and flip 18.

i outta be studying for a fluid mech. exam, but this riddle keeps distracting me…

{Ken starts warming up his vintage Cray 1}

Choose a common coin type, let’s say you feel US dimes. Put the dimes in one group and the rest of the coins in a different group. Bingo, 2 groups of coins
EDIT: Oops, forgot about the heads up part.

Jack has left the box :^)

some coins wont stand on their edge

how bout, put 25 in your left pocket, and 25 in your right pocket?

(no heads are showing in either pocket)

Ken took the money and ran^

The room is dark -> group anyway you want - neither group has any heads showing : zero == zero

as you pick up each coin, cut it in half

put the two halfs in separate piles

or better yet, you get an elephant, a bowling ball, and 4 pounds of wax…

Denman
October 18, 2005, 3:15pm
10
lol
i don’t know the answer either
its bothering me

get an elephant, a bowling ball, and 4 pounds of wax…
the rest is intuitively obvious

this is my standard answer for all brainstorming sessions, no matter what the question or problem is

Why don’t you just turn on the light, and then flip over the coins?

Denman
October 18, 2005, 3:37pm
13
because it defeats the object of the excercise
lol

I knew that, but then Ken said something about some elephant so I thought I was entitled to say something about the lights.

Was this a homework assignment or something?

I think I reasoned it out, I had the right idea on my first post, but the wrong number

the original pile has 32 heads up, so you take 32 from the pile and flip them over. That is your second pile.

If you grabbed all 32 heads then there are no heads left in either pile

if you grabbed 18 heads and 18 tales, then you left 18 heads in the first pile, and when you flip the second pile you have 18 heads in both piles

if you grabbed 19 heads and 17 tales, then you left 17 heads in the first pile, and when you flip the second you have 17 heads and 19 tails

it works for all combinations

but I like the pocket answer better :^)

KenWittlief:

I think I reasoned it out, I had the right idea on my first post, but the wrong number

the original piles has 32 heads up, so you take 32 from the pile and flip them over. That is your second pile.

If you grabbed all 32 heads then there are no heads left in either pile

if you grabbed 18 heads and 18 tales, then you left 18 heads in the first pile, and when you flip the second pile you have 18 heads in both piles

if you grabbed 19 heads and 17 tales, then you left 17 heads in the first pile, and when you flip the second you have 17 heads and 19 tails

it works for all combinations

but I like the pocket answer better :^)

Ken,

Last time I checked, 18+18=36 not 32.

Mike

KenWittlief:

I think I reasoned it out, I had the right idea on my first post, but the wrong number

the original piles has 32 heads up, so you take 32 from the pile and flip them over. That is your second pile.

If you grabbed all 32 heads then there are no heads left in either pile

if you grabbed 18 heads and 18 tales, then you left 18 heads in the first pile, and when you flip the second pile you have 18 heads in both piles

if you grabbed 19 heads and 17 tales, then you left 17 heads in the first pile, and when you flip the second you have 17 heads and 19 tails

it works for all combinations

but I like the pocket answer better :^)

Your answer is right but the explanation is wrong:

The original piles has 32 heads up, so you take 32 from the pile and flip them over. That is your second pile.

If you grabbed all 32 heads then there are no heads left in either pile

if you grabbed 18 heads and 14 tales, then you left 14 heads in the first pile, and when you flip the second pile you have 14 heads in both piles

if you grabbed 19 heads and 13 tales, then you left 13 heads in the first pile, and when you flip the second you have 13 heads and 19 tails

it works for all combinations

Regards,

Mike

Are you sure thats the riddle? I did a bunch of googling (Try googling a riddle :rolleyes: ) so yeah here is what i came up with.
“You are wearing a blindfold and thick gloves. An infinite number of quarters are laid out before you on a table of infinite area. Someone tells you that 20 of these quarters are tails and the rest are heads. He says that if you can split the quarters into 2 piles where the number of tails quarters is the same in both piles, then you win all of the quarters. You are allowed to move the quarters and to flip them over, but you can never tell what state a quarter is currently in (the blindfold prevents you from seeing, and the gloves prevent you from feeling which side is heads or tails). How do you partition the quarters so that you can win them all?”
uh i also found a forum based on this riddle. http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_hard;action=display;num=1028100705

Denman
October 18, 2005, 5:59pm
19
it was actually just something that my friend said to me
i don’t have a clue where he got it from

Which one of the states is infinately large?
What state is on the back of all the quarters?
Do you know what breed of horse is on the back of the Delaware quarter?

…A quarterhorse.