Question 7.27

7.27 Alcohol content in beer.

In February 2013, two California residents filed a class-action lawsuit against Anheuser-Busch, alleging the company was watering down beers to boost profits.12 They argued that because water was being added, the true alcohol content of the beer by volume is less than the advertised amount. For example, they alleged that Budweiser beer has an alcohol content by volume of 4.7% instead of the stated 5%. CNN, NPR, and a local St. Louis news team picked up on this suit and hired independent labs to test samples of Budweiser beer. The following is a summary of these alcohol content tests, each done on a single can of beer.

bud

4.94 5.00 4.99
  1. Even though we have a very small sample, test the null hypothesis that the alcohol content is 4.7% by volume. Do the data provide evidence against the claim of 5% alcohol by volume?
  2. Construct a 95% confidence interval for the mean alcohol content in Budweiser.
  3. U.S. government standards require that the alcohol content in all cans and bottles be within of the advertised level. Do these tests provide strong evidence that this is the case for Budweiser beer? Explain your answer.

7.27

(a) . The data are significant and provide evidence that the alcohol content is not 4.7%. (b) (4.897, 5.057). (c) To be within 0.3% of the advertised level, they need to be between 4.7% and 5.3%. Because our confidence interval is entirely within this range, it appears that Budweiser is within the standards.