Concept:Mean = (Sum of all the observations/Total number of observations)Deviation = ? |X “ µ|Here, ? represents the addition of valuesX represents each value in the data setµ represents the mean of the data setCalculation:Sum of the deviations x1, x2, x3 ...... xn, from 100 is -20.? (x1 - 100) + (x2 - 100) + (x3 - 100) + ......... +(xn - 100) = - 20? x1 + x2 + x3 + .......... + xn - 100n = - 20? x1 + x2 + x3 + ........... + xn = 100n - 20 ------(i)Sum of deviations of the values from 92 is 140? (x1 - 92) + (x2 - 92) + (x3 - 92) + .......... + (xn - 92) = 140? x1 + x2 + x3 + ......... + xn - 92n = 140? 100n - 20 - 92n = 140 [Using (1)]? 8n = 160? n = 20Thus the total number of observations is 20.So, sum of observations = x1 + x2 + x3 + ....... + xn = 100 x 20 - 20 = 2000 - 20 = 1980And hence, mean of the data is 1980/20 = 99.? The mean of the values is 99.