Question

Fuel Efficiency of Manual and Automatic Cars

Each year the US Environmental Protection Agency (EPA) releases fuel economy data on cars manufactured in that year. Below are summary statistics on fuel efficiency (in miles/gallon) from random samples of cars with manual and automatic transmissions manufactured in 2012. Do these data provide strong evidence of a difference between the average fuel efficiency of cars with manual and automatic transmissions in terms of their average city mileage? Assume that conditions for inference are satisfied.

	City MPG, Automatic	City MPG, Manual
Mean	16.12	19.85
SD	3.58	4.51
n	26	26

The hypotheses for this test are:

• Ho: μ_automatic = μ_manual
  Ha: μ_automatic ≠ μ_manual

The test statistic is: -3.30

The p-value is:  (please round to four decimal places)  

Interpret the result of the hypothesis test in the context of the problem:

• The data provide sufficient evidence that there is no difference between the average fuel efficiency of manual and automatic cars in terms of their average city mileage (I'm able to get everything but the p-value. I keep getting .0018. I'm not sure what I am doing wrong)

Answer 1

The p value which you got for the two tailed hypothesis is correct only. i have attached the screenshot of p value calculator below.