The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is-
A. 45 B. 50 C. 51.4 approx D. 54.6 approx Answer: Option CShow Answer
Solution(By Apex Team)
Let the required mean score be x
Then,
$\begin{array}{l}
20 \times 80+25 \times 31+55 \times x=52 \times 100 \\
\Leftrightarrow 1600+775+55 x=5200 \\
\Leftrightarrow 55 x=2825 \\
\Leftrightarrow x=\large\frac{2825}{55} \approx 51.4
\end{array}$
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