4. Suppose we have collected data on the exam grades and divided them according to gender, with the information contained in the following table: Table 2: Exam grades & gender Males Females number of observations 16 18 Standard deviation 4.2 2.3 mean 69 63 (a) Is there any statistical evidence that the standard deviation of exam grades for male students is larger than the standard deviation of grades for female students? Use a significance level of a = 1%. [35 marks] (b) Conduct a test to assess whether there is a statistically significant difference in the average grades between male and female students. Use a a = 1% significance level. [35 marks]