The mean marks obtained by 1,200 boys in an exam is 72 with a standard deviation of 10, while the mean marks obtained by 1,000 girls is 70 with a standard deviation of 8.
Test at the 1% significance level whether boys and girls differ significantly in their mean marks.
Explain the procedure of testing the significance of the difference of means for large samples. State the formula for the test statistic and the assumptions used.