Thursday, November 12, 2009

The Case of a Missing Dollar

You buy $60 worth of products at the store and give the cashier 3 x $20. The cashier is scanning your store loyalty card and congratulates you on receiving $5 off from your purchase. She then asks whether you would like to contribute to a local charity. You agree to give $2, and then she gives you the remaining $3 back.
So, overall you paid $60 - $3 = $57
There are also $2 you gave to the charity. $57 and $2 are $59 total.
But you started with $60, where is the additional dollar?

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!


Wang said...

I like this puzzle.

The additional dollar is not missing, it's just that the problem is that money is added up strangely.

You gave $57 and you should be adding $3 because that is what you got back in change - not what you gave to charity.

If for instance, you bought $55 of stuff and then gave $4 in charity then the question would ask

Overall you paid $60 - $1 = $59, but then you gave $4 in charity so you actually paid $63 !!!! Where did the extra $3 come from?

Maria said...

You got the trick!
First puzzle for W, who also made a very sophisticated comment on a birthday cake puzzle.

New one tomorrow!

kj said...

It is unclear whether the $55 price includes the $5 discount or not. This does not change the answer.

You give $60 for a $55 purchase, and should receive $5 change. You donate $2 of the change, and so receive $3 from the cashier.

Here is the mistake:
There are also $2 you gave to the
charity. $57 and $2 are $59 total.

You have added the $2 donation to the wrong number. You should instead say "$55 and $2 are $57 total" as in order to find how much you spent you add the purchase price and the donation.

Maria said...

Thank you for the good clarification, Kimberly.

rubix journal said...

now i got confused :)

Maria said...

You entered the store with $60, left there $57 and still have $3 in your wallet.

From the $57 you left at the store, $55 goes for the items you purchased and $2 to the charity.

The puzzle tries to confuse you to add $2 to $57 again.

Anonymous said...

The dollar was always there. The addition they gave was wrong. First add $2 to the $60. Subtract $5 then add $3. You get $60

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