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Winners from last weeks math problem, and the new problem of the week

Submitted by david.thacker on Fri, 10/03/2014 - 15:45

The Disappearing Dollar Answer

This mystery is an excellent example of why it is important to read things carefully - in math and in other subjects.  The trick here are the words "plus the $2 tip for the waiter".  Instead of adding the $2 ({plus the $2 tip"), you should subtract it. Think about it.  subtract that $2 and you get $25, which is the amount the restaurant got.  Each friend got $1 and the waiter got $2.

Another way of thinking about it is to remember that the friends also shared the cost of the $2 tip ($0.67) each).  So they paid $9 for their share of the meal and their share of the tip.  The food itself cost each friend $8.33, then the $0.67 tip took that to $9.  So if each paid $10 and got $1 back, then everything really does work out.

Winners:Ryan Berger, Gavin Campbell, Peyton Christensen, Aleeta Jo Eyre, Aaron Farnsworth, Amanda Graham, Megan Graham, Andrew Gunyan, Maddy Johnson, Robert LaPray, Bryce Marshall, Tyson McNeil, Morgan Olson, Brennan Peine, Matthew Whitaker, Alex Webb

Our new math problem of the week is:

Pizza Peril

The Challenge:

It's your first day of work at Catwalk magazine, a dream come true.  You're starting out as a lowly editorial assistant, but if you're patient and enthusiastic, then maybe one day you'll be flying off to Milan and Paris to check out the latest collections. 

But that's still a daydream.  For the moment you're the assistant to the glamorous Catwalk editor, Corey DiFerro - one of the toughest people in the business.  People say that she chews up designers, photographers, receptionists - and probably - editorial assistants - and spits them out.  And you never did find out why the last editorial assistant at Catwalk lasted only one day.

You're outside the main editorial office when the door opens and someone calls to you, "Ms. DiFerro wants you - NOW!!

Inside, there's a group huddled around the main table.  You recognize fashion designers, supermodels, two pop stars, photographers....and Corey DiFerro, looking you straight in the eye.

"Right. Do we have your attention?  Look, we're off on a photo shoot in half an hour and we need some lunch first.  Pizza - it's quick.  DaNoi down on Seventh Avenue doesn't deliver, so I want you to go out and get some for us.  Plain cheese only.  Now, how hungry is everyone?  I'll call your name and you tell my assistant how much you want."

Scala twins?"

"One slice each."

"Art department?"

"Two pizzas."


"Half a pizza."

"Copy editors?"

"We'll share one pizza."


"Three slices."

"Steve, our faithful driver?"

"One - one pizza, that is."

"And I'll have one slice," says Ms. DiFerro.  She hands you a roll of bills and sends you off saying, "They only take cash.  Don't take too long."

On the elevator down, you count out the cash - 90 exactly.  Will that be enough?  You don't have any cash of your own in case you run short.  And anyway, you don't have time to stop for more money.

At DaNoi you're standing on tiptoes to see over the other customers.  Each pizza is cut into 12 slices - no exception.  And the person ahead of you has just paid $36 for two pizzas.

It's your turn now.  Will you have enough money - and will you have a job tomorrow?

Please send an email to with your answer.