The laboratory of a pharmaceutical company is asked to evaluate the claim that the mean concentration μ of the active ingredient in a drug manufactured by the company is 0.80%. The data from four samples of the drug have mean y = 0.82% and sample standard deviation s = 0.01%. The distribution of the concentration of the active ingredient in this drug can be approximated by a normal model.

Question 1. Which of the following is a 99% confidence interval for the mean μ? (right click on this link to open a t-table in a new window).

(0.7994%, 0.8406%)

(0.8071%, 0.8329%)

(0.7908%, 0.8492%)

(0.7616%, 0.8784%)

Question 2. Using the above data, suppose we wished to test the claim using the hypotheses
H0: μ = 0.80%

Ha: μ ≠ 0.80%
at a 1% significance level. What should we conclude?

we cannot test these hypotheses because we cannot both test hypotheses and use confidence intervals

we do reject H0

we do not reject H0

we do not have enough information to determine whether we reject H0