A company that makes cola drinks states that the mean caffeine content per 12-ounce bottle of cola is 50 milligrams. You want to test this claim. During your tests, you find that a random sample of thirty 12-ounce bottles of cola has a mean caffeine content of 50.9 milligrams. Assume the population is normally distributed and the population standard deviation is 7.5 milligrams. At α=0.05, can you reject the company's claim?
a. Find the critical value(s). Select the correct choice below and fill in the answer box within your choice.
b. Find the standardized test statistic.