Problem Solving

I took alllll sorts of math classes throughout highschool and college but never Stats and Probability! Could someone walk me through this a bit?

Greatly appreciated!

-Matt

Melinda’s lights went out. She has 3 pairs of red socks in her drawer, 2 pairs of black socks, and 5 pairs of white socks. What is the minimum number of pairs she must remove from the drawer to ensure that she has a pair of each color?


A 3
B 5
C 7
D 9
E 10

Ok this is a logical problem.

Since you need to find the minimum number of pairs you must consider the worst case.

We have 3p - red socks, 5p - white and 2p - black.

Worst case would make one pick all white and all red and then one black.

So the number = 5+3+1 =9.

ans is d.

Take a look at the GMAT Math Review by GMAC. It has a complete introdution of Stats or Probablity