The following scores represent the final examination grades for an elementary statistics course: (5 marks) 79, 99, 77, 91, 81, 84,52, 52, 72,55, 64, 67, 52, 71, 75, 57, 85, 66, 65, 89, 83, 73, 64, 81, 71, 74, 54, 68, 24,3 19, 15, 17,20 41,45, 31, 65, 42,39 a. Find the sample mean and sample median. b. Construct a stem-and-leaf plot for the examination grades in which the stems are 1, 2, 3,..9. c. Construct a relative frequency histogram.