Question

The rates of on-time flights for commercial jets are continuously tracked by the U.S. Department of Transportation. Recently, Southwest Air had the best reate with 80 % of its flights arriving on time. A test is conducted by randomly selecting 13 Southwest flights and observing whether they arrive on time. (a) Find the probability that exactly 9 flights arrive late.

Answer 1

P(flights arriving late) = 1 - 0.8 = 0.2

n = 13

It s a binomial distribution

P(X = x) = nCx * p^x * (1 - p)^{n - x}

P(X = 9) = 13C9 * (0.2)^9 * (0.8)^4 = 0.00015