Question

In a class of 70 students. the ratio of the boys to the girls is 9 : 5. In a test, the average score of the girls is 40% more than that of the boys. If the average score of all the students is 120, then what is the average score of boys and girls?
1. 110 and 154
2. 105 and 147
3. 147 and 105
4. 154 and 110

Answer 1

Correct Answer - Option 2 : 105 and 147

Given:

Number of students = 70

Average score of girls is 40% more than boys

Concept used:

Average = (Total of all the variables/ No. of variables)

Calculation:

Number of boys and girls are 45 and 25

Let boys' average marks be 5x

Girls' average marks = 7x

45 × 5x + 25 × 7x = 120 × 70

⇒ 225x + 175x = 8400

⇒ 400x = 8400

⇒ x = 21

⇒ 5x = 105

⇒ 7x = 147

∴ Average score of boys and girls is 105, 147