The data below shows the mean scores in the post-test of two sample groups of students taught using two different methods of teaching mathematics. METHOD A METHOD B X1 = 80 X2 = 90 0 = 8 02 = 10 ni= 20 n2=10 Formulate a null hypothesis about the population mean Formulate an alternative hypothesis for (a) two-tailed test and (b) a one-tailed test.