Problem continued below. The cumulative frequency for the first three classes is?

Question

The following data revealed the number of hours of television watched by 130 five year olds on a Saturday.
0 - 2 hrs: 15
3 - 5 hrs: 40
6 - 8 hrs: 45
9 - 11 hrs: 20
12 - 14 hrs: 10
.

Then the cumulative frequency for the first three classes is?

.

a. 120

b. 55

c. 100

d. 130

e. none of these

Answer 1

Cumulative frequency is just the sum of the frequencies of all the classes before it.

So the cumulative frequency for the first three classes is the frequency of the first class (15) plus the frequency of the second class (40) plus the frequency of the third class (45):

15 + 40 + 45 = 100, answer c.