Two Population Means with Known Standard Deviations · Exercise 19

DIRECTIONS: For each of the word problems, use a solution sheet to do the hypothesis test. The solution sheet is found in. Please feel free to make copies of the solution sheets. For the online version of the book, it is suggested that you copy the.doc or the.pdf files.

Some manufacturers claim that non-hybrid sedan cars have a lower mean miles-per-gallon (mpg) than hybrid ones. Suppose that consumers test 21 hybrid sedans and get a mean of 31 mpg with a standard deviation of seven mpg. Thirty-one non-hybrid sedans get a mean of 22 mpg with a standard deviation of four mpg. Suppose that the population standard deviations are known to be six and three, respectively. Conduct a hypothesis test to evaluate the manufacturers claim.

This is an open-ended exercise: its source gives no single answer.

OpenStax, Introductory Statistics 2e · §10.2 Two Population Means with Known Standard Deviations · Exercise 19