Question

An automobile manufacturer claims that its van has a 34.6 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 34.9. Assume the standard deviation is known to be 2.3. A level of significance of 0.1 will be used. Make a decision to reject or fail to reject the null hypothesis. Make a decision.

reject null hypothesis

or

fail to reject null hypothesis

Answer 1

Solution :

This is the two tailed test .

The null and alternative hypothesis is ,

H0 :   = 34.6

Ha : 34.6

Test statistic (z) =  

= ( - ) / / n

= (34.9 - 34.6) / 2.3 / 220

Test statistic = 1.93

P-value = 0.0530

= 0.10

P-value <

Reject the null hypothesis .