Since the variance is unknown, it is necessary to test the mean value U by T-test. Assuming H0: u ≤ 88 and H2:u2≥88, the following command can be input in Matlab to solve it: x = [85 67102 87 90 76 56]; M = 88h=ttest(x, m, 0.05,' right'); The final result is h= 0, which means that the original hypothesis cannot be rejected when the significance level is 0.05. In other words, people who exercise less than 30 minutes weigh less than 88kg on average.

Regarding the specific principle of t-test, we can look at probability theory and mathematical statistics. I wonder if it will help you. You can ask if you don't know. I hope to give a compliment!