Ajit, Ravi and Hari were trying to hit a target. If Ajit hits the target 5 times in 8 attempts, Ravi hits it 3 times in 5 attempts and Hari hits it 2 times in 4 attempts. What is the probability that the target is hit by at least 2 persons ?

Probability of Ajit = 5/8
Probability of Ravi = 3/5
Probability of Hari = ½
Probability that the target is hit by at least 2 persons = 1 - [Prob of no hit + Prob of 1 hit].
=$$1-\left(\frac{3}{8}\times\ \frac{2}{5}\times\ \frac{1}{2}+\frac{5}{8}\times\ \frac{2}{5}\times\ \frac{1}{2}+\frac{3}{8}\times\ \frac{3}{5}\times\ \frac{1}{2}+\frac{3}{8}\times\ \frac{2}{5}\times\ \frac{1}{2}\right)$$
= $$1-\frac{31}{80}=\frac{49}{80}$$