In an examination, the average marks of a student per paper were 71. If he would have obtained 35 more marks in sciences; 11 more marks in history and 4 more marks in computer science, his average marks per paper would have been 76. How many papers were there in the examination?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 10
Let there are n papers.
Sum of scores in 'n' papers = n × 71 = 71n
After increment of scores, sum of scores in 'n' papers = 71n + 35 + 11 + 4 = 71n + 40.
Average becomes = 76
(71n + 50)/n = 76
71n + 50 = 76n
5n = 50
n = 10.