Interesting combination problem!
Thanks for the help!
GMATPrep question 24
This topic has expert replies
-
- Senior | Next Rank: 100 Posts
- Posts: 41
- Joined: Thu Nov 08, 2007 3:22 pm
The idea is total combination = combination of chairs x combination of tables.
Since we know it's 150 total combos possible that MUST mean : combo of chairs x combo tables
Chair combo is known to be : 5!/2!3! = 5 x 2 = 10
Thus combo of tables = 15 = x! / 2!(x-2)!
Work it backwards and you'll find that the only way to get 30 = x(x-1) is if x = 6
Hope that helped!
Since we know it's 150 total combos possible that MUST mean : combo of chairs x combo tables
Chair combo is known to be : 5!/2!3! = 5 x 2 = 10
Thus combo of tables = 15 = x! / 2!(x-2)!
Work it backwards and you'll find that the only way to get 30 = x(x-1) is if x = 6
Hope that helped!
Work Hard, Play Harder!