Question

A company that makes shampoo wants to test whether the average amount of shampoo per bottle is 16 ounces. the standard deviation is known to be 0.20 ounces. assuming that the hypothesis test is to be performed using 0.10 level of significance and a random sample of n = 64 bottles, how large could the sample mean be before they would reject the null hypothesis?

Answer 1

Answer: n=64 is large enough to use a z-test. The two-tailed 90% confidence interval (5% in each tail) is pop. mean +/- 1.64 (s.d. / sqrt(n) ) = 16 +/- 1.64 * 0.2/8 oz = [15.959, 16.041]oz m