Question

A cell phone company offers two plans to its subscribers. At the time new subscribers sign up, they are asked to provide some demographic information. The mean yearly income for a sample of 40 subscribers to Plan A is $47,200 with a standard deviation of $9,200. For a sample of 30 subscribers to Plan B, the mean income is $51,500 with a standard deviation of $7,100. At the .01 significance level, is it reasonable to conclude the mean income of those selecting Plan B is larger? Hint: For the calculations, assume the Plan A as the first sample.

The test statistic is_______ . (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)

Answer 1

The statistical software output for this problem is:

Hence,

Test statistic = -2.21