Monday, May 26, 2008

7.11

I was waiting to get on a poker table at Bally's a couple of weeks back. I was donning my beautiful Rutgers sweatshirt. Here's a picture of it



R-U, rah rah, R-U, rah rah, HOO-rah, HOO-rah, Rutgers RAH!

So some guy also waiting for a table spots my sweatshirt and comes up to start up a conversation. Turns out, he taught math at Rutgers many years ago. We share our backgrounds, and he says, "Well, here's something to think about while you're playing..." He added a story that made the question more of a "riddle" than just a math question, but here is the core of it:

In a "seven-eleven" (7-11) store, a customer selected four items to buy. The check-out clerk says that he multiplied the costs of the items and obtained exactly 7.11, the very name of the store! The customer calmly tells the clerk that the costs of the items should be added, not multiplied. The clerk then informs the customer that the correct total is also $7.11. What are the exact costs of the 4 items?

I went to my 1-3 No-Limit table while he went to his 2-4 Limit table. While I was playing, during hands I wasn't in, the math geek in me got control of me and I started to try to work it out. Distracted from both the game and the problem, I put it aside intending to try more later. I got home and searched for the problem, intending to blog about it, and accidentally spotting the solution. Annoyed because I'll never know if I would've been able to figure it out, I post it here as a challenge.

You can find the solution if you google...

1 comment:

ChuckJerry said...

I worked on it for about an hour before I looked up the answer. I posted the problem to a brain teasers forum that I like to read and some guys came up with the answer through a computer program.

http://brainden.com/forum/index.php?showtopic=2848&st=0&gopid=36048&#entry36048

The answer is so far away from the prime factors of 3, 3, and 79 that I would have been working for a while before I had actually gottne this on my own.