Statistics help!

• Nov 28th 2007, 02:06 PM
monkeydoodie
Statistics help!
Question:

10 Honda Civic owners and 12 Toyota Corolla owners were randomly selected, and asked about their cars gas mileage. Yielded the following:

Honda - 28.5, 31.0, 29.6, 26.8, 36.2, 32.4, 30.8, 27.4, 26.6, 29.7.
Toyota - 31.2, 24.8, 28.5, 27.1, 34.9, 26.1, 25.7, 28.8, 29.6, 19.8, 35.0, 26.6.

Assuming that the standard deviations of mph are equal.

A) Find a 99% CI for the difference of their means of mpg.
B) Test the claim that Honda's have better mph with level 0.05.

I'm not just looking for answers however solutions (step by step) to the problems in which I can apply and use for future similar problems. The textbook I am using doesn't quite clearly explain how to set this up and solve.

Thanks in advance! I really appreciate the assistance!
• Nov 28th 2007, 02:23 PM
TKHunny
Calculate the Means.
Calculate the Variances.

Let's see if you can get that far. In the cae of statistics, the step-by-step solution IS the answer. Learning the process is the plan.
• Nov 28th 2007, 02:44 PM
monkeydoodie
I was hoping for a more detailed response so I can study the relationship of the data to the problem per an upcoming exam (per urgent homework help).

However,

XBAR1 (Honda) - 28.5, 31.0, 29.6, 26.8, 36.2, 32.4, 30.8, 27.4, 26.6, 29.7 = 299

299/n
n=10
29.9

Deviation for each number and square of each deviation:
28.5-29.9 = -1.4 & 1.96
31.0-29.9 = 1.0 & 1.21
29.6-29.9 = -.3 & .09
26.8-29.9 = -3.1 & 9.61
36.2-29.9 = 6.3 & 39.69
32.4-29.9 = 2.5 & 6.25
30.8-29.9 = .9 & .81
27.4-29.9 = -2.5 & 6.25
26.6-29.9 = -3.3 & 10.89
29.7-29.9 = -.2 & .04

Sum of all squares of deviations = 67.16

67.16 / n - 1
67.16 / 9
7.46222

XBAR2 (Toyota) - 31.2, 24.8, 28.5, 27.1, 34.9, 26.1, 25.7, 28.8, 29.6, 19.8, 35.0, 26.6 = 338.1

338.1/n
n=12
28.175

...
• Nov 28th 2007, 02:50 PM
monkeydoodie
I'll be out the door in about 30 minutes. =/