Subway footlongs are supposed to be 12 inches long. You strongly suspect that Subway is up to its old tricks and is reducing the size of its delicious sandwiches. For your research, you randomly sample Subways and eat 10 sandwiches. You find the average size of the sandwich to be 11.5 inches with a standard deviation of .9 inches. You want to now test if subway sandwiches are less than their advertised size.
(A) Set up the null and the alternative hypothesis. What is your test statistic? What is the critical statistics? Test at the 80% significance level. Based on your evidence, is Subway shortchanging customers? Should you sue?
Suppose you now eat an additional 10 sandwiches for a total sample size of 20 sandwiches. The mean of your sandwiches is still 11.5 inches with a standard deviation of .9 inches.
(B) Set up the null and the alternative hypothesis. What is your test statistic? What is the critical statistics? Test at the 95% significance level. Based on your evidence, is Subway shortchanging customers? Should you sue? How do your findings change?