PART II Different teachers using different methods taught methods taught two groups of students. Both groups of students sat the same Exam Frequency Frequency examination at the end of the course. Mark Group A Group B 20-29 1 1 30-39 3 2 40-49 6 4 50-59 6 13 60-69 11 15 70-79 10 6 80-89 8 3 a) Find the mean exam mark for each group. [2+2 marks] b) Which teaching method is better? Give a reason for your answer. [2 marks] 1 AY B E SS