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.

A) Does the data provide evidence to conclude that students performance in math is increased. Use 5% level of significance.

(B) Without calculation, say the 95% CI for the true difference provide the same conclusion or not.