Consumer Reports rated airlines and found that 80% of the flights involved in the study arrived on time (that is, within 15 minutes of scheduled arrival time). Assuming that the on-time arrival rate is representative of the entire commercial airline industry, consider a random sample of 180 flights. (Round your answers to two decimal places.)

What is the expected number that will arrive on time?

What is the standard deviation of this distribution?

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Mathematics

25 November, 23:05

Consumer Reports rated airlines and found that 80% of the flights involved in the study arrived on time (that is, within 15 minutes of scheduled arrival time). Assuming that the on-time arrival rate is representative of the entire commercial airline industry, consider a random sample of 180 flights. (Round your answers to two decimal places.)

What is the expected number that will arrive on time?

What is the standard deviation of this distribution?

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Caroline Wilson · Answer 1

Expected number = mean = 144

Standard deviation = 5.37

Step-by-step explanation:

As you have two options (on time / delay) we are talking about using a Binomial distribution.

Expected number that will arrive on time is the same as expected value (mean).

mean = expected value = np = (180) (0.8) = 144

std dev = √[np{1-p) ] = √[180{0.8 * (1-0.8) }] = √[180{0.8*0.2) }] = 5.37