The number of students in a class is 45, out of which 33% are boys and the rest are girls. The average score of girls in Science is 66% more than that of boys. If the average score of all the students is 78, then the average score of girls is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 90.
Number of boys = 1/3 × 45 = 15
The number of girls = 30.
The average score of girls in Science is 66% more than that of boys.
Let the average score of boys be 3x and for girls be 5x.
According to the question,
(15 × 3x + 30 × 5x) = 45 × 78.
45x + 150x = 3510.
x = 18.
Average score of girls = 5x = 5 × 18 = 90.