| Score | 0 – 4 | 5 – 9 | 10 – 14 |
| Frequency | 2 | 1 | 2 |
The table shows the distribution of the scores of some students in a test. Calculate the mean scores.
- 5.6
- 6.2
- 6.6
-
7.0
The correct answer is: D
Explanation
To calculate the mean of grouped data,
- First step to determine the midpoint (x) of each interval or class.
0 - 4 ►2
5 - 9 ► 7
10 - 14 ►12
These midpoints must then be multiplied by the frequencies of the corresponding classes:
2 X 2 = 4
1 X 7 = 7
2 X 12 = 24
Mean = ( 24 + 7 + 4) ÷ ( 2 + 1 + 2 )
: Mean = 7