For Exercises 9–14, the frequency distribution is provided for a particular variable. Do the following:

  1. Find the class midpoints.
  2. Calculate the product of each class frequency with its midpoint.
  3. Find the sum of the frequencies, , and the sum of the products .
  4. Divide by to find the estimated mean of the variable, .

Question 3.222

9.

Class Frequency
2
10
13
5

3.3.9

(a)-(c)

Class Frequency Midpoint Product ·
2 0.5 1.0
10 1.5 15.0
13 2.5 32.5
5 3.5 17.5
Total

(d)