Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work. Class Frequency 76-78 16 79-81 5 82-84 10 85-87 13 88-90 8 Solution The class mark represents the class value and is the average of the class limits. 1st: 77 2nd: 80 3rd: 83 4th: 86 5th: 89 -------- Multiply each class mark by the class frequency and add those products Divide by the total of the frequencies to get the mean = 82.8 standard deviation = 4.01 The variance is the square of the standev = 4.01^2 = 16.11.