The number of students in a class is 45, out of which $$33\frac{1}{3}\% $$ are boys and the rest are girls. The average score of girls is Science is $$66\frac{2}{3}\% $$ more than that of boys. If the average score of all the students is 78, then the average score of girls is:
A. 54
B. 65
C. 78
D. 90
Answer: Option D
Solution(By Examveda Team)
Number of students = 45Number of boys = $$33\frac{1}{3}\% $$ of 45 = 15
Number of girls = 45 - 15 = 30
Obtain marks of girls in science subject is $$66\frac{2}{3}\% $$ more then the obtain marks of boys.
$$\eqalign{ & 66\frac{2}{3}\% = \frac{2}{3} \cr & \frac{{{\text{Girls}}}}{{{\text{Boys}}}} = \frac{{5x}}{{3x}} \cr} $$
Total marks
15 × 3x + 30 × 5x = 45 × 78
3x + 2 × 5x = 3 × 78
13x = 3 × 78
x = 3 × 6
x = 18
5x = 18 × 5
5x = 90
Related Questions on Percentage
A. $$\frac{1}{4}$$
B. $$\frac{1}{3}$$
C. $$\frac{1}{2}$$
D. $$\frac{2}{3}$$
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