Exhibit 3-1
The following data show the number of hours worked by 200 statistics students.
-Refer to Exhibit 3-1. The class width for this distribution
A)is 9
B)is 10
C)is 11
D)varies from class to class

Question

Exhibit 3-1
The following data show the number of hours worked by 200 statistics students. 
-Refer to Exhibit 3-1. The class width for this distribution
A)is 9 
B)is 10 
C)is 11 
D)varies from class to class

Quizplus · Accepted Answer

To find the class width, we need to subtract the lower limit of one class from the lower limit of the next class. The smallest data entry is 1 and the largest is 48, so the range is 48-1=47. To find the number of classes, we can use the square root rule (which is not precise, but is useful for estimation): sqrt(200)≈14. Therefore, we will choose 14 classes with a width of 47/14≈3.36. Rounding this up to the nearest whole number gives us a class width of 4. The class boundaries are:
0.5-4.5, 4.5-8.5, 8.5-12.5, 12.5-16.5, 16.5-20.5, 20.5-24.5, 24.5-28.5, 28.5-32.5, 32.5-36.5, 36.5-40.5, 40.5-44.5, 44.5-48.5.
The class width is the same for all classes, so the correct answer is B.

Exhibit 3-1 the Following Data Show the Number of Hours Worked by Worked