Question

The ratio between the marks obtained in Unit test by P and Q is 3 : 4. But due to wrong question each student get 5 marks as a bonus, then the ratio of marks obtained in Unit test by P and Q is 7 : 9. Find the difference between the original marks obtained by Q and P in Unit test.
1. 10
2. 25
3. 30
4. 15
5. 21

Answer 1

Correct Answer - Option 1 : 10

Given:

Let marks obtained by P and Q in unit test be 3a and 4a respectively.

⇒ (3a + 5) : (4a + 5) = 7 : 9

⇒ 27a + 45 = 28a + 35

⇒ a = 10

The original marks obtained by P = 3 × 10 = 30

The original marks obtained by Q = 4 × 10 = 40

∴ Required difference = 40 - 30 = 10