Answer:
There is no enough evidence that the repair cost for type I ovens is greater than the repair cost for type II ovens.
Step-by-step explanation:
We have to perform a hypothesis test on the difference of two means.
Type I ovens:
- Sample mean: 70.15
- Sample standard deviation: 20.62
- Sample size: 43
Type II ovens:
- Sample mean: 65.36
- Sample standard deviation: 22.21
- Sample size: 57
Step 1. The claim is that the repair cost for type I ovens (μ1) is greater than the repair cost for type II ovens (μ2). The null and alternative hypothesis are:
Step 2.
The difference between the sample means is:
The standard error of the difference between means is:
The degrees of freedom are:
The t-statistic is
Step 3. The critical value for a right tail test with significance level of 0.05 and 98 degrees of freedom is t=1.66.
Then, if the test statistic is higher than 1.66, the effect is significant and the null hypothesis is rejected (rejection region).
If not, the null hypothesis is not rejected (acceptance region).
Step 4. The t-statistic is below the critical value, so the null hypothesis is not rejected.
There is no enough evidence that the repair cost for type I ovens is greater than the repair cost for type II ovens.