In order to increase their efficiency, one group of operators was imparted classroom training, and the other group was provided on the job training. After the training, the times to complete a certain job in minutes, was recorded for both the groups, the data recorded is given in the following table.

Classroom Training On Job Training
Operator No- Time Operator No- Time
1 35 1 85
2 39 2 28
3 51 3 42
4 63 4 37
5 48 5 61
6 31 6 54
7 29 7 36
8 41 8 57
9 55