what is the p-value for rats before and after using a diet pill , at a 5% level

before, in kg, 2.7, 3.2, 4.1, 3.5, 2.6, 3.7, 2.8

after, in kg; 3.2, 1.9, 4.2, 2.5, 2.9, 2.6, 3.2, 3.8, 2.1