An anti-aircraft gun takes a maximum of four shots at an enemy plane moving away from it. The probabilities of hitting the plane at first, second, third, and fourth shot are 0.4, 0.3, 0.2, and 0.1 respectively. The probability that the gun hits the plane then is:
Explanation
1. Define the Probabilities of Hitting
Let P(H1),P(H2),P(H3), and P(H4) be the probabilities of hitting the plane on the 1st, 2nd, 3rd, and 4th shots respectively.
-
P(H1)=0.4
-
P(H2)=0.3
-
P(H3)=0.2
-
P(H4)=0.1
2. Find the Probabilities of Missing
The probability of missing a shot is 1−P(Hit).
-
P(Miss1)=1−0.4=0.6
-
P(Miss2)=1−0.3=0.7
-
P(Miss3)=1−0.2=0.8
-
P(Miss4)=1−0.1=0.9
3. Calculate the Probability of Missing All Shots
The gun fails to hit the plane only if it misses all four shots. Since the shots are independent:
P(Miss all)=P(Miss1)×P(Miss2)×P(Miss3)×P(Miss4)
P(Miss all)=0.6×0.7×0.8×0.9
4. Calculate the Probability of Hitting the Plane
The probability of hitting the plane is the complement of missing all shots:
Correct Option: (c) 0.6976