Question

11. An automobile manufacturer claims that its van has a 54.5 miles/gallon (MPG) rating. An independent testing firm has been contracted to test the MPG for this van since it is believed that the van has an incorrect manufacturer's MPG rating. After testing 220 vans, they found a mean MPG of 54.2. Assume the variance is known to be 4.84. A level of significance of 0.01 will be used. Make a decision to reject or fail to reject the null hypothesis. Make a decision.

12. Determine the critical values for the confidence interval for the population variance from the given values. Round your answers to three decimal places.

n=27 and c=0.8.

Answer 1

11)

since test statistic does not falls in rejection region we fail to reject null hypothesis

12)

Critical value of chi square distribution for n-1=26 df and 80 % CI
Lower critical value χ2L=		17.292
Upper critical valueχ2U=		35.563