question_answer

Let P, Q and R try to hit the target simultaneously but independently. Their respective probabilities of hitting the targets are \[\frac{3}{4},\] \[\frac{1}{2}\]and\[\frac{5}{8}\] . The probability that the target is hit by A or B but not by C is ________.

A)  \[\frac{7}{8}\]                         

B)  \[\frac{7}{32}\]

C)  \[\frac{9}{64}\]                        

D)  \[\frac{21}{64}\]

E)  None of these