# Let the following sample of 8 observations be drawn from a normal population with unknown mean…

Let the following sample of 8 observations be drawn from a

normal population with unknown mean and standard deviation: 21, 20,

25, 18, 28, 19, 13, 22. [You may find it useful to reference the t

table.]

a. Calculate the sample mean and the sample standard deviation.

(Round intermediate calculations to at least 4 decimal places.

Round “Sample mean” to 3 decimal places and “Sample standard

deviation” to 2 decimal places.)

b. Construct the 90% confidence interval for the population

mean. (Round “t” value to 3 decimal places and final answers to 2

decimal places.)

c. Construct the 99% confidence interval for the population

mean. (Round “t” value to 3 decimal places and final answers to 2

decimal places.)

d. What happens to the margin of error as the confidence level

increases from 90% to 99%? As the confidence level increases, the

margin of error becomes larger. As the confidence level increases,

the margin of error becomes smaller.