What is the cumulative frequency up to and including the 15-19 class?

What is the cumulative frequency up to and including the 15-19 class?

• A. 5
• B. 10
• C. 11
• D. 12

Answer: (B)

Cumulative frequency up to a class means the total number of observations that fall in all classes from the smallest up to and including that class. To get it, you add the frequencies of every class from the start up to the 15–19 class. It’s not just the number in the 15–19 class itself. In this distribution, summing all frequencies up to and including 15–19 gives 10, so the cumulative frequency is 10. The other options would correspond to sums that exclude or include different portions of the distribution.

Cumulative frequency up to a class means the total number of observations that fall in all classes from the smallest up to and including that class. To get it, you add the frequencies of every class from the start up to the 15–19 class. It’s not just the number in the 15–19 class itself.

In this distribution, summing all frequencies up to and including 15–19 gives 10, so the cumulative frequency is 10. The other options would correspond to sums that exclude or include different portions of the distribution.