Friday, September 14, 2007

Math Problem #1

Well, seeing how there is a lot more math in my life recently, I think I'll start up a weekly or bi-weekly math problem slash brain-teaser for you to test your meddle.

Tonight's problem is actually from my friend Andrew's dad. He's been teaching a math club at the elementary school Andrew and I went to 15 years ago. He's continued to teach this math club that goes to Math Olympiad every year to compete, even though his youngest son is now 25. He and I went to the Mariners game tonight and we got to talking math. I asked him if there were any problems that have stood out over his years, and the first one that popped into his head was this one:

A+B+C=20
A+B+D=25
A+C+D=30
B+C+D=28

A+B+C+D=???

Oh, and of course: show your work! :)

I was trying to do this in my head while watching the baseball game, it took me a good 5 innings to figure it out, with many hints along the way. But feel free to use notepad or some paper and a pencil. If you need a hint, check out the comment section. Good luck!

And go Mariners! Walk-off sacrifice fly by Guillen to win in the bottom of the 9th!

Labels:

2 Comments:

Blogger meanhappyguy said...

You're not necessarily dealing with whole numbers, but they are real numbers.

Extra credit:
A=?
B=?
C=?
D=?

10:43 PM  
Blogger Mr Subliminal said...

Not very difficult, but good fun. Thanks.

A+B+C=20 (Equation 1)

A+B+D=25 (Equation 2)

A+C+D=30 (Equation 3)

B+C+D=28 (Equation 4)

D-C=5 (2-1)

A-B=2 (3-4)

C-B=5 (3-2)

C-A=3 (4-2)

A=B+2

C=A+3 =B+5

D=C+5 =B+10

But A+C+D=30

So 3B+17=30

B=13/3

A=19/3

C=28/3

D= 43/3

A+B+C+D=103/3

1:45 PM  

Post a Comment

Subscribe to Post Comments [Atom]

<< Home