Let G=good looking and N= not good looking. Then if we pick a couple at random we either get GG (p=0.1x0.1) GN (p=0.1x0.9) NG (p=0.9x0.1) or NN (p=0.9x0.9) We are told we get one of the first three (p=0.01+0.09+0.09=0.19) and we want the probability that it is the first of these (p=0.01). Hence answer is 0.01/0.19.