Question

A study found that the mean amount of time cars spent in​ drive-throughs of a certain​ fast-food restaurant was 137.2 seconds. Assuming​ drive-through times are normally distributed with a standard deviation of 30 ​seconds, complete parts​ (a) through​ (d) below.

(a) What is the probability that a randomly selected car will get through the​ restaurant's drive-through in less than 99 ​seconds?

The probability that a randomly selected car will get through the​ restaurant's drive-through in less than 99 seconds is ___. ​(Round to four decimal places as​ needed.)

​(b) What is the probability that a randomly selected car will spend more than 182 seconds in the​ restaurant's drive-through?

The probability that a randomly selected car will spend more than 182 seconds in the​ restaurant's drive-through is ___. ​(Round to four decimal places as​ needed.)

​(c) What proportion of cars spend between 2 and 3 minutes in the​ restaurant's drive-through?

The proportion of cars that spend between 2 and 3 minutes in the​ restaurant's drive-through is __. ​(Round to four decimal places as​ needed.) ​

(d) Would it be unusual for a car to spend more than 3 minutes in the​ restaurant's drive-through?​ Why?

The probability that a car spends more than 3 minutes in the​ restaurant's drive-through is nothing​, so it (would not, would) be​ unusual, since the probability is ▼(less, greater) than 0.05. ​(Round to four decimal places as​ needed.)

Answer 1