Junior school research team would like to examine whether students performance in math is increased after recruiting two high qualified math teachers. Both pre-test and post-test scores of a random sample of 20 students was recoded. The mean difference between post-test and pre-test score was 15.4 with standard deviation 3.4. Does the data provide evidenceto conclude that students performance in math is increased. Use 5% level of significance. Find 95% CI for the true difference and make conclusion on hypothesis.

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