Question

As reported by a recent​ survey, the​ fast-food restaurant with the best​ drive-through time had a mean time spent in the​drive-through of

mu equals 63.6μ=63.6

seconds. Assuming​ drive-through times are normally distributed with

sigma equals 2.9σ=2.9

​seconds, complete parts ​(a) through ​(d) below.

​(a) What is the probability that a randomly selected car will get through the​ drive-through in less than

60.360.3

​seconds?The probability is

nothing.

​(Round to four decimal places as​ needed.)​(b) What is the probability that a randomly selected car will spend more than

70.370.3

seconds in the​ drive-through?The probability is

nothing.

​(Round to four decimal places as​ needed.)​(c) What proportion of cars spend between

60.360.3

and

70.370.3

seconds in the​ drive-through?

nothing

​(Round to four decimal places as​ needed.)​(d) Would it be unusual for a car to spend more than

70.370.3

seconds in the​ drive-through?

A.​Yes, because the probability of randomly choosing a car that waits more than

70.370.3

seconds in the​ drive-through is less than​ 5%.

B.​No, because the probability of randomly choosing a car that waits more than

70.370.3

seconds in the​ drive-through is less than​ 5%.

C.​Yes, because the probability of randomly choosing a car that waits more than

70.370.3

seconds in the​ drive-through is greater than​ 5%.

D.​No, because the probability of randomly choosing a car that waits more than

70.370.3

seconds in the​ drive-through

Answer 1

=1-P(Z<2.31)

=1-0.9896

=0.0104

A.​Yes, because the probability of randomly choosing a car that waits more than 70.3 seconds in the​ drive-through is less than​ 5%.