The following information was obtained from matched samplestaken from two populations. The daily production rates for a sample of workers before and after a training program are shown below.Assume the population of differences is normally distributed.

Worker	Before	After
1	20	22
2	25	23
3	27	27
4	23	20
5	22	25
6	20	19
7	17	18

The point estimate for the difference between the means of the two populations is?

The null hypothesis to be tested is H₀: _d = 0. The test statistic is?

Given that the null hypothesis to be tested is H₀: _d = 0, should null hypothesis be revised or rejected?