Suppose that vehicles arrive at a fast food drive-through at a

rate of 20 cars per hour. A random sample of 40 one hour time

periods is taken between 12:00 noon and 1:00 pm and it is

found that the average number of cars arriving per hour is

22.1.

a.

Why is the sampling distribution of x bar

approximately normal?

dovrintion of the

In the study of probability theory, the central limit theorem (CLT) states that the distribution of sample means approximates a normal distribution. The average is a result of common characteristic within the group. As a general rule, sample sizes equal to or greater than 30 are deemed sufficient for the CLT to hold, anything less - ie; daily d=20 x 1ph may mean less cars) it becomes a general rule, where sample sizes equal to or greater than 30 are deemed sufficient for the CLT to hold