1 Answers

Option 1 : 20

Given:

Average number of students who cleared the exam = 65

Calculation:

Let the number of girls and boys who cleared the exam be 11a and 15a respectively.

⇒ 11a + 15a = 65 × 2 = 130

⇒ a = 5

Girls students and boys students who cleared exam = 55 and 75

Let the number of girls and boys who didn't clear the exam be N.

⇒ (55 + N) : (75 + N) = 7 : 9

⇒ 495 + 9N = 525 + 7N

⇒ N = 15

Total number of Girls students in college = 55 + 15 = 70

Total number of boys students in college = 75 + 15 = 90

 Required difference = 90 – 70 = 20

∴ the correct answer is 20.

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