Question 194362
Worst case scenario:


She pulls out all 5 pairs of white socks, then all 3 pairs of red socks, and then finally pulls out a pair of black socks. So in the worst case, she has to pull out 5+3+1=9 pairs of socks to guarantee that she has a pair of each color. 



Note: this is the worst case because she has to do the most work to guarantee a solution.