In: Statistics and Probability
When the author visited Dublin, Ireland, he recorded the ages of randomly selected passenger cars and randomly selected taxis. The ages can be found from the license plates. The ages in years are listed below. We might expect that taxis would be newer, so test the claim that the mean age of cars is greater than the mean age of taxies.
Car Ages: 4 0 8 11 4 14 3 3 7 6 6 6 15 9
Taxi Ages: 8 8 0 3 4 4 6 0 5 9 3 4
What is the null hypothesis? What is the alternative hypothesis?
What is the p-value and the test statistic?
Do we reject the null or fail to reject the null?
Write a conclusion.
x : Car Ages
y : Taxi Ages
x | y | x-x̅ | y-y̅ | (x-x̅)2 | (y-y̅)2 | |
4 | 8 | -2.8571 | 3.5 | 8.1633 | 12.25 | |
0 | 8 | -6.8571 | 3.5 | 47.0204 | 12.25 | |
8 | 0 | 1.1429 | -4.5 | 1.3061 | 20.25 | |
11 | 3 | 4.1429 | -1.5 | 17.1633 | 2.25 | |
4 | 4 | -2.8571 | -0.5 | 8.1633 | 0.25 | |
14 | 4 | 7.1429 | -0.5 | 51.0204 | 0.25 | |
3 | 6 | -3.8571 | 1.5 | 14.8776 | 2.25 | |
3 | 0 | -3.8571 | -4.5 | 14.8776 | 20.25 | |
7 | 5 | 0.1429 | 0.5 | 0.0204 | 0.25 | |
6 | 9 | -0.8571 | 4.5 | 0.7347 | 20.25 | |
6 | 3 | -0.8571 | -1.5 | 0.7347 | 2.25 | |
6 | 4 | -0.8571 | -0.5 | 0.7347 | 0.25 | |
15 | 8.1429 | 66.3061 | ||||
9 | 2.1429 | 4.5918 | ||||
Total= | 96 | 54 | 0 | 235.7143 | 93 | |
mean=x̅ | Total/14 | Total/12 | ||||
x̅= | 6.8571 | 4.5 |