Three different brands of pain relief medication are available for minor aches and pains

Three different brands of pain relief medication are available for minor aches and pains. It is of interest to know whether the mean time to relieve the pain differs from brand to brand. To find out, twelve individuals with minor aches and pains were randomly assigned to one of the three brands. The time to relieve the pain (in
minutes) for each individual is provided in the table below.
Brand A Brand B Brand C
I0 I5 20
l2 22 25
I5 25 20
I4 I9 11

Given that the necessary assumptions are satisfied, can it be concluded. at the 2.5%
level of significance, that not all mean times to relieve pain are equal? Formulate
and test the appropriate hypotheses. Use the critical value approach.