Refer to the accompanying data display that results from a sample of airport data speeds in Mbps. Complete parts(a) through(c) below.

Tinterval

(13.046,22.15)

x=17.598

Sx=16.01712719

n=50

a. Express the confidence interval in the format that uses the"less than" symbol. Given that the original listed data use one decimalplace, round the confidence interval limits accordingly.

______Mbps < <________ Mbps (Round to two decimal places asneeded.)

b. Identify the best point estimate of and the margin of error.

The point estimate of is _______ Mbps. (Round to two decimal places asneeded.)

The margin of error is E=________ Mbps. (Round to two decimal places asneeded.)

c. In constructing the confidence interval estimate of , why is it not necessary to confirm that the sample data appear to be from a population with a normaldistribution?

A. Because the sample size of 50 is greater than30, the distribution of sample means can be treated as a normal distribution.

B. Because the sample standard deviation isknown, the normal distribution can be used to construct the confidence interval.

C. Because the population standard deviation isknown, the normal distribution can be used to construct the confidence interval.

D. Because the sample is a randomsample, the distribution of sample means can be treated as a normal distribution.