A sample of students in a Professor's Statistics course scored the following grades on their first test shown below.
74, 78, 82, 83, 85, 86
a. Calculate $\sum x_i$ (? pronounced 'sigma', means the sum of; $x_i$ are the individual values) = 488
b. If n represents the total number of scores, calculate (rounded to the nearest tenth) $\frac{\sum x_i}{n}$ = 81.3