4. The marks of 30 students on a statistics examination were collected randomly as shown below 87 79 94 60 75 94 77 83 68 74 82 73 63 75 77 83 92 591 64 53 53 82 73 90 55 68 72 88 65 78 (a) Using the classes 50-59, 60-69, 70-79, 80-89, 90-99, construct a frequency distribution table. [4] (b) Calculate the mean, mode and median. [16] (c)I. Comment of the distribution, whether or not it is symmetrical, positively skewed or negatively skewed. [1] II. If the distribution is symmetrical (Normal Distribution Curve), outline all the characteristics of the Normal Distribution Curve. [8]