\(\begin{array}{c|c} Scores & 0 - 4 & 5 - 9 & 10 - 14\\ \hline
MATHEMATICS
WAEC 2015
\(\begin{array}{c|c}
Scores & 0 - 4 & 5 - 9 & 10 - 14\\
\hline Frequency & 2 & 1 & 2\end{array}\)
The table shows the distribution of the scores of some students in a test. Calculate the mean scores.
- A. 5.6
- B. 6.2
- C. 6.6
- D. 7.0
Correct Answer: D. 7.0
Explanation
To calculate themean 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
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