The number of students in class 9th end class 10th is 42 and 45, respectively. The ratio of the number of boys to girls in classes is 9th and 10th is 9 : 5 and 8 : 7, respectively. What is the difference between the total number of boys and the total number of girls in both the classes taken together
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 15.
If the ratio of boys and girls in class 9th is 9 : 5
Then, the number of boys = (9/14) × 42 = 27
And, the number of girls = (5/14) × 42 = 15
If the ratio of boys and girls in class 10th is 8 : 7
Then, the number of boys = (8/15) × 45 = 24
And, the number of girls = (7/15) × 45 = 21
Number of boys in both classes = 27 + 24 = 51
Number of girls in both classes = 15 + 21 = 36
Difference = 51 - 36 = 15