The probability of a radar station detecting an enemy plane is 0.65 and the probability of not detecting an enemy plane is 0.35. If 20 stations are in use, what is the expected number of stations that will detect an enemy plane?
A)20
B)0
C)18
D)13
E)none of these choices

Question

Quizplus · Accepted Answer

The expected value of detecting an enemy plane for one station is:
0.65(detected) * 1 + 0.35(not detected) * 0 = 0.65
So for 20 stations, the expected number of stations that will detect an enemy plane is:
20 * 0.65 = 13
Therefore, the answer is D.

The Probability of a Radar Station Detecting an Enemy Plane