34. Price of Milk. The U.S. Bureau of Labor Statistics reports that the mean price for a gallon of milk in June 2014 was $3.63. Suppose that we have a random sample taken this year of 400 gallons of milk, and assume that the population standard deviation equals $1.00. We want to conduct a hypothesis test, using level of significance , to investigate if the population mean price of milk this year has increased.