- Home
- Standard 13
- Quantitative Aptitude
4.Average
medium
The arithmetie 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
Solution
Let the number of students be $100.$
Then total score $=52 \times 100=5200$
first $20 \%$ scored $=20 \times 80=1600$
last $25 \%$ scored $=25 \times 31=775$
$\therefore$ Remaining $55 \%$ student's score $=5200-1600-775=2825$
$\therefore$ Average score among $55 \%=\frac{2825}{55}=51.4$ approx
Standard 13
Quantitative Aptitude
