THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING:
A recent survey found that 40% of all air traffic controllers found their job extremely stressful.Suppose 12 air traffic controllers are selected at random.
-What is the probability that two or more of them consider their job extremely stressful?
A)0.7218
B)0.9804
C)0.0282
D)0.2806

Question

Quizplus · Accepted Answer

The probability that two or more air traffic controllers find their job extremely stressful can be found by subtracting the probability of none or only one finding their job extremely stressful from 1. The probability of exactly k controllers finding their job stressful follows a binomial distribution with parameters n = 12 (number of trials) and p = 0.4 (success probability). The probability of none (k=0) or one (k=1) finding their job stressful can be calculated using the binomial probability formula. Subtracting this sum from 1 gives the probability of two or more finding their job stressful, which is closest to option B, 0.9804.