Dilbert decides he needs a new job. He begins working at a computer repair store, fixing laptops, desktop computers, and tablets. His new position requires him to track the number of repairs made to each computer (both major and minor). The store only works on two major brands of computers, and data for last month's repairs are given below. Note that the "average" is of the number of repairs per computer.
| Manufacturer |
n |
Average |
Standard Deviation |
| A |
17 |
3.4 |
1.2 |
| B |
21 |
4.7 |
1.7 |
A) What conditionns or assumptions must be considered before doing any inference procedures?
B) Find a 99% confidence interval for the difference in mean number of repairs made. You do not need to interpret this interval
C) Test whether there is a difference in the mean number of repairs between the two manufactureers. Use alpha = 0.01