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 3.225

12.

Class Frequency
5
10
15
20
20