solve all 3 questions

( marks) QUESTION THREE [20 MARKS] The table below shows the distribution of marks scored by Statistics 2nd year students in a statistics course: Marks 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 Freq. 4 7 8 9 11 15 5 Free Using an assumed mean method, calculate the mean and the standard deviation of Marks students' marks (9 marks) b) Calculate the coefficient of kurtosis and interpret your results (5 marks) c) Calculate the difference between the 7th decile and the 57th percentile. (6 marks)