问题
单项选择题
Xavier, Y vonne, and Zelda each try independently to solve a problem. If their individual probabilities for success are 
and 
, respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem ？（）
A.A
B.B
C.C
D.D
E.E
答案
参考答案：E
解析：
根据题意可知X解出此问题的概率为[*]，Y解出此问题的概率为[*]，而Z解不出题目的概率为[*]，因此X和Y解出此题而Z解不出此题的概率为：[*]