Probability question

[raniu]

Xavier, Yvonne, and Zelda each try independently to solve a problem. If their individual probabilities for success are 1/4, 1/2 and 5/8 , respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem ?
(A) 11/8
(B) 7/8
(C) 9/64
(D) 5/64
(E) 3/64

Can someone please explain the solution to this problem? Thanks.

[dkpbus]

Probablity that Zelda will not be able to solve problem is 1 - 5/8 = 3/8 hence

Required Probablity = 1/4*1/2*3/8 = 3/64

Answer is E