Three persons P, Q and R independently try to hit a target. If the probabilities of their hitting the target are 3/4, 1/2 and 5/8 respectively, then the probability that the target is hit by P or Q but not by R is?

We have to find the probability when P hits, Q hits, and R does not hit. This can be represented as P∩Q∩R'.

The probabilities are given as:
P = 3/4
Q = 1/2
R = 5/8
Therefore, R' (R does not hit) = 1 - 5/8 = 3/8

The probability that P hits and Q hits and R does not hit is:
P(P∩Q∩R') = P(P) * P(Q) * P(R') = (3/4) * (1/2) * (3/8) = 9/64

Therefore, the probability that the target is hit by P or Q but not by R is 9/64. The options provided seem to be misformatted; the correct answer expressed as a fraction is 9/64, not one of the options listed.