Eleven white socks and six red socks are in a drawer. If two socks are selected at random, what is the probability that both socks are the same color?

either RR or WW

prob of RR = (6/17)(5/16) = 15/136
prob of WW = (11/17)(10/16) = 55/136

prob of same colour = 70/136 = 35/68