Question

A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. SUVs equipped with tires using compound 1 have a mean braking distance of 79 feet and a standard deviation of 7.3 feet. SUVs equipped with tires using compound 2 have a mean braking distance of 86 feet and a standard deviation of 8.8 feet. Suppose that a sample of 79 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVs equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ1 be the true mean braking distance corresponding to compound 1 and μ2 be the true mean braking distance corresponding to compound 2. Use the 0.1 level of significance.

Do we reject or refuse to reject the null hypothesis?

Answer 1