In an examination, the average marks of a student per paper were 72. If he had got 25 fewer marks in Mathematics and 17 more marks in Science, his average marks per paper would have been 71. How many papers were there in the examination?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 8.
Let the number of papers = x
Original total marks = 72x
25 less in Math, 17 more in Science
Net change = -25 + 17 = -8
New total marks = 72x - 8
New average = 71
⇒ = 71
⇒ 72x - 8 = 71x
⇒ x = 8