Question

5. A sample of 120 body builders have an average weight of of 278.20 pounds and a sample standard deviation of 12.62 pounds. Construct a 99% confidence interval estimate the mean of the weight of bodybuilders for the entire population.

a) Find the margin of error, E

b) What is the Confidence Interval?

c) Interpret the confidence interval.

Answer 1

Sample mean, = 278.20 pounds

Standard deviation, = 12.62 pounds

Sample size, n = 120

Corresponding to 99% confidence interval, the z score = 2.575

(a) Margin of error, E = = 2.967

(b) The confidence Interval is ()

= (275.233, 281.167) pounds

(c) With 99% confidence, the population mean weight of bodybuilders is between 275.233 pounds and 281.167 pounds, based on 120 samples