单选题
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?
and, respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem?
【正确答案】
E
【答案解析】[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：
，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：