A group is interested in seeing if the mean gas mileages from two different brands of gasoline are the same. To test this, they sampled 20 cars that used Type A gas and 16 cars that used Type B gas. From these samples, they calculated the following descriptive statistics (in terms of miles per gallon): Type A Gas Type B Gas ?n 20 16 ?⎯⎯⎯x¯ 29 29 ?s 4 7 (Assume the samples are independent and that the populations are normally distributed with unknown mean and standard deviation) (a) Is there significant evidence to suggest that there is a difference in gas milage? Test this at the ?=0.05α=0.05 significance level. State your conclusions regarding H0 (b) Calculate a 95% confidence interval for the true difference of the means. State your conclusions after calculating the interval.
A group is interested in seeing if the mean gas mileages from two different brands of gasoline are the same. To test this, they sampled 20 cars that used Type A gas and 16 cars that used Type B gas. From these samples, they calculated the following
| Type A Gas | Type B Gas | |
| ?n | 20 | 16 |
| ?⎯⎯⎯x¯ | 29 | 29 |
| ?s | 4 | 7 |
(Assume the samples are independent and that the populations are
(a) Is there significant evidence to suggest that there is a difference in gas milage? Test this at the ?=0.05α=0.05 significance level. State your conclusions regarding H0
(b) Calculate a 95% confidence interval for the true difference of the means. State your conclusions after calculating the interval.
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