A Riddle That'll Kill Your Brain!

[inaminute]

I believe the answer is one.

Mary is the only customer who went to the apple stand, where she purchased 1/2 of his one remaining apple, plus the other half of the one apple.

The others all went to John's store.

 

[rgf207]

I can see some are stumped by this one.

Mickeyfan your answer can't work because if John had 11 apples mary would have to buy 6 apples not 7 1/2 of 11 + 1/2 is 6 not 7.

 

[mickeyfan2]

1/2(11)+1/2=6
1/2(11-6)+1/2=3
1/2(11-6-3)+1/2=1 1/2 <=but there can't be a cut apple so I don't think this works.

Mathematically, I keep coming up with 3, but that doesn't seem to work for Betty and her 1/2 apple.
John starts with 3
Mary buys 2
Sue buys 1
Betty buys 0

That is why I belive my first answer is correct. Each time you divide by 2 the numerator must be an odd number so when you add 1/2 the total is a whole number. For there to be none left after talking 1/2 of the remainder and 1/2 of an apple the remainder would have to equal 1/2 of itself + 1/2 an apple so the last remainder would have to be 1.

As we see 1 does not work.

 

[rgf207]

I believe the answer is one.

Mary is the only customer who went to the apple stand, where she purchased 1/2 of his one remaining apple, plus the other half of the one apple.

The others all went to John's store.

Nope... This is not a trick question either. They all went to see John' and bought apples from John. There is a mathematical solution for this. A friend of mine is a math teacher and gives this problem to his student's parents when they visit for parent's day. It's not a trick

 

[mickeyfan2]

I can see some are stumped by this one.

Mickeyfan your answer can't work because if John had 11 apples mary would have to buy 6 apples not 7 1/2 of 11 + 1/2 is 6 not 7.

Yes it should have been 6. I typed the wrong number.

 

[rgf207]

do you all want a hint ?

 

[mickeyfan2]

The only possible starting number of apples to keep both divisions with an odd number are 3, 7, 11, 15 etc.
3 and 11 don't work
15+ will leave a remainder

So he must start with 7 apples

Mary buys 4 apples
Sue buys 2 apples
Betty buys 1 apple
That leaves John with no apples

 

[rgf207]

The only possible starting number of apples to keep both divisions with an odd number are 3, 7, 11, 15 etc.
3 and 11 don't work
15+ will leave a remainder

So he must start with 7 apples

Mary buys 4 apples
Sue buys 2 apples
Betty buys 1 apple
That leaves John with no apples

You got it