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

test statistic is −2.13

Plan A  first sample.

Plan B Second sample.

( 2 )Rejection Region

(5) Conclusion

It is concluded that the null hypothesis Ho is not rejected. Therefore it not reasonable to conclude the mean income of those selecting Plan B is larger  at the 0.01 significance level.