Question

120 psychology students took a standardized test. the scores are summarized in the frequency distribution table below.

scores	frequency
160 - 179	14
180 - 199	15
200 - 219	19
220 - 239	13
240 - 259	43

the scores are also described in the cumulative table shown below.

scores	frequency
less than 180	30
less than 200	45

| less than 220 |

less than 240	77
less than 260	120

what is the missing value in the cumulative frequency distribution table?
answer =

Explanation:

Step1: Recall cumulative - frequency concept

Cumulative frequency is the sum of frequencies of all previous classes and the current class.

Step2: Calculate missing value

The cumulative frequency of "less than 220" is the sum of the frequencies of scores in the ranges 140 - 159, 160 - 179, 180 - 199 and 200 - 219. We know that the frequency of 140 - 159 is 16, 160 - 179 is 14, 180 - 199 is 15 and 200 - 219 is 19. So, $16 + 14+15 + 19=64$.

Answer:

64