Question

Suppose a phone company reports that the average duration of phone calls is 1.7 minutes, with standard deviation of 1.4 minutes.

Now suppose that you want to examine a random sample of 60 phone calls. Do you think it would be reasonable to use the Central Limit Theorem to describe the sampling distribution of the sample mean call duration?

a. Yes, the CLT applies because the standard deviation is smaller than the mean.

b. Yes, the CLT applies because both (sample size)*(pi)≥10 and (sample size)*(1-pi)≥10

c. Yes, the CLT applies because the distribution of call duration is symmetrical.

d. Yes, the CLT applies because the sample size is greater than 30.

e. No, the CLT does not apply because the distribution of the mean call duration is not symmetrical.

f. None of these.

Answer 1

Sol:

since sample size

n>30

large sample

follows normal distribution

according to central limit theorem.

MARK OPTION

d. Yes, the CLT applies because the sample size is greater than 30.