1. Below are the final grades of 30 introductory statistics students. 53; 57; 57; 63; 65; 66; 67; 68; 68; 70; 71; 73; 73; 73; 74; 74; 74; 74; 75; 76; 76; 76; 77; 80; 81; 83; 83; 86; 90; 95 a) Calculate the mean. Now, to avoid the tedious calculation of the deviance for each individual data point, the same grades have been grouped by decile. Use the sample mean from part a) to fill in the table. Decile Frequency Midpoint Deviations Deviations Frequency x Deviations m (m - if) (m - If)2 fx (m - if)2 50-59 3 60-69 6 70-79 14 80-89 4 90-99 2 Total: Efx (m - x;)? = Using the results from the table, calculate b) the sample variance, $2. c) the sample standard deviation, s