IIT-JEE 1981Question 1
An anti-aircraft gun can take a maximum of four shots at an enemy plane moving away from it. The probabilities of hitting the plane at the first, second, third and fourth shot are $0.4$, $0.3$, $0.2$ and $0.1$ respectively. What is the probability that the gun hits the plane?
Probability
Answer$0.6976$
Solution
$P(\text{no hit})=0.6\cdot0.7\cdot0.8\cdot0.9=0.3024$, so $P(\text{hit})=1-0.3024=0.6976$.