Exhibit 2-1
The numbers of hours worked (per week) by 400 statistics students are shown below.
-Refer to Exhibit 2-1. The cumulative relative frequency for the class of 20 - 29
A)is 300
B)is 0.25
C)is 0.75
D)is 0.5

Question

Exhibit 2-1
The numbers of hours worked (per week) by 400 statistics students are shown below. 
-Refer to Exhibit 2-1. The cumulative relative frequency for the class of 20 - 29
A)is 300 
B)is 0.25 
C)is 0.75 
D)is 0.5

Quizplus · Accepted Answer

The cumulative relative frequency for a class is the sum of the relative frequencies for that class and all previous classes. The relative frequency for the class 20-29 is 0.15 and the relative frequency for the class 10-19 is 0.10. Therefore, the cumulative relative frequency for the 20-29 class is 0.15 + 0.10 = 0.25. Since this is the cumulative relative frequency up to and including the 20-29 class, it means that 25% of the students have worked 20-29 hours per week or less. Thus, the correct answer is C.

Exhibit 2-1 The Numbers of Hours Worked (Per Week) by 400 Statistics