Choko Ltd provides training to its salespeople to aid the ability of each salesperson to increase the value of their sales. During the last training session 15 salespeople attended, and their weekly...

Choko Ltd provides training to its salespeople to aid the ability of each salesperson to increase the value of their sales. During the last training session 15 salespeople attended, and their weekly sales before and sales after are provided in Table 6.8.

Assuming that the populations are normally distributed, assess whether there is any evidence that the training improves sales (test at 5% and 1%).