\(\begin{array}{c|c}
Scores & 0 - 4 & 5 - 9 & 10 - 14\\
\hline Frequency & 2 & 1 & 2\end{array}\)
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
Correct answer is D
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