[EX09-183] A box of Corn Flakes that is labeled

“NET WT. 14 OZ.” should have 14 oz or more of cereal inside. Twenty of these boxes were randomly selected and the weight of the contents

(in ounces) determined. 14.52 14.47 14.80 14.60 14.45 14.25 14.15 14.12 14.36 14.39 14.50 14.29 14.28 14.60 13.85 14.18 14.39 14.45 14.69 14.38

a. Draw a histogram of the weight of cereal per box.

b. Find the sample statistics mean and standard deviation.

c. What percent of the sample is below the 14.0 oz weight?

The plant foreman is studying the filling process and needs to estimate the mean weight of all boxes being filled.

d. Determine whether an assumption of normality is reasonable. Explain.

e. Find the 95% confidence interval for the mean weight

f. The filling process is believed to be running with a standard deviation of fill of no more than 0.2 oz. Test this hypothesis at the 0.01 level.