Please help

Attempt all the questions that follow .. @ccording to recent information from the Kenya Automo%ile Association, the mean age of passenger cars in Kenya is 8.4 years. A sample of 40 cars in the student's lot at CMU showed the mean age to be 9.2 years. The standard deviation of this sample was 2.8 years. At the 0.01 significance level can we conclude that the mean age for these cars ofCMU students is more than 8.4 years? (a)State the null hypothesis and the alternative hypothesis for this test. (b) Explain why 2 is the test Statistic to be used. (c) What is the critical value of this test statistic? (d)Compute the value of the test statistic (e)what is your decision regarding the null hypothesis? Interpret your decision