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Where Knowledge Junkies Get Their Fix
Meet Hal. He’s a successful commercial artist. He’s also the guy at work who never seems to have change for a dollar for the vending machine. Hal wastes time every day going from desk to desk asking his co-workers for change.
Today, Hal happened to have
some coins in his pocket.All but two of them were nickels,
all but two of them were quarters,
and all but two of them were pennies.How much change did Hal have?
Here is the ANSWER.
Comments (10)
Comment
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couldn’t he have also had 20 cents?
posted by bill on 3-26-2009 at 10:12 am
No, 31 cents is the only acceptable answer.
Here’s the “mathy” way of doing this.
Let x be the total number of coins he has. So N+Q+P=x.
Now since all but 2 of the coins are nickles, we can say that N=x-2. Similarly Q=x-2 and P=x-2.
Putting N, Q, and P into the first equation gives you (x-2)+(x-2)+(x-2)=x which solves for x=3. Thus there must be one of each coin.
Apropos reCaptcha: and publish
posted by Tom in GA on 3-26-2009 at 10:25 am
Tom you’re right with the equation, but you forgot some variables. The equation should be P + N + D + Q + H + $ = X
We know how many pennies nickels and quarters he has but we know nothing about dimes half-dollars or dollar coins, so we also have valid answers where P,N,Q = 0 and D+H+$=2
So the correct answers would be .31 (penny, nickel and quarter)
.20 (2 dimes)
.60 (dime and half-dollar)
1.00 (2 half-dollars)
1.10 (dime and dollar)
1.50 (half-dollar and dollar)
2.00 (2 dollars)
posted by Eli on 3-26-2009 at 11:09 am
True… but saying “all but two of them were nickels” implies that there were nickels in his pocket, and so on with quarters and pennies.
I don’t know the actual theory behind it, but it seems like you couldn’t assume that other variables were involved if they weren’t mentioned in the problem. I mean, for that matter, he could have had foreign coins… but that’s just an assumption.
posted by Sandy Wood on 3-26-2009 at 11:28 am
$0.20 is also a correct answer. If he has two dimes, it is perfectly correct to say that every coin in his pocket is a nickel except for two of them. Misleading, duh, but 100% true.
posted by Matt on 3-26-2009 at 12:50 pm
There’s a riddle like this that goes: if you have two coins and they total 30 cents, what are they if one of them is not a quarter. The answer is a nickel and a quarter. The nickel is the coin that is “not a a quarter.”
That said, I don’t think you can say that you have two dimes in your pocket and say that every coin in your pocket is a nickel except two of them (the two dimes). Saying that you have a group of something except part of it implies that you have something from the first group to begin with. Otherwise, there is no “exception.” The two dimes make up the entire contents of your pocket.
posted by john on 3-26-2009 at 1:36 pm
Going to have to agree with Bill and Matt on this one; that was my thinking as well.
posted by Will on 3-26-2009 at 2:28 pm
I got the answer correct but take exception with the plurality of the words “quarters, nickles and pennies”. Doesn’t this imply that there was more than one quarter, one nickel and one penny?
posted by WillieO on 3-26-2009 at 3:21 pm
No, because the total number of coins is unknown, and grammatically speaking it is correct to use the plural there.
Plus, “all but two is a quarter” sounds bad and kind of ruins the puzzle. Maybe if this were Sesame Street and not Mental Floss… :)
posted by Ryan on 3-26-2009 at 4:46 pm
when .50 cent was a teenager… .20 cent baby!! just had to throw that in there
posted by jeff on 3-26-2009 at 5:14 pm