SOLUTION This is a test of two independent groups, two population means, population standard deviations known. Random Variable: = difference in the mean number of months the competing floor waxes last. Ho: = μ1 μ2 > Ha: μ1 μ2 The words says that "is more effective" wax 1 lasts longer than wax 2, on the average. "Longer" is a ">" symbol and goes into Ha. Therefore, this is a right-tailed test. Distribution for the test: The population standard deviations are known so the distribution is normal. Using the formula above, the distribution is:
SOLUTION This is a test of two independent groups, two population means, population standard deviations known. Random Variable: = difference in the mean number of months the competing floor waxes last. Ho: μ1 = μ2 Ha: μ1 > μ2 The words "is more effective" says that wax 1 lasts longer than wax 2, on the average. "Longer" is a ">" symbol and goes into Ha. Therefore, this is a right-tailed test. Distribution for the test: The population standard deviations are known so the distribution is normal. Using the formula above, the distribution is: