Question

The scores on a test for a sample of 42 statistics students are summarized in the following table. 9, 90, 18, 80, 15, 70. Find the mean score. round your answer to at least one decimal place.

Answer 1

Answer:   78.6

Work Shown:

$\begin{array}{|c|c|} \cline{1-2}\text{Number of People} & \text{Score}\\\cline{1-2}9 & 90\\\cline{1-2}18 & 80\\\cline{1-2}15 & 70\\\cline{1-2}\end{array}$

Multiply across the rows to form a third column. Example: 9*90 = 810 in the first row.

$\begin{array}{|c|c|c|} \cline{1-3}\text{Number of People} & \text{Score} & \text{Number*Score}\\\cline{1-3}9 & 90 & 810\\\cline{1-3}18 & 80 & 1440\\\cline{1-3}15 & 70 & 1050\\\cline{1-3}\end{array}$

The values in the third column add to 810+1440+1050 = 3300

Divide this over the total number of people which is 9+18+15 = 42

The mean is 3300/42 =78.571 approximately which rounds to 78.6