Question

In an examination, there are three papers each of 100 marks. A candidate obtained 53 marks in the first and 75 marks in the second paper. How many marks must the candidate obtain in the third paper to get an overall of 70 per cent marks?

Answer 1

Let x be the marks of the candidate in the third paper.

Then total marks secured in all those papers = 53 + 75 + x

Total marks of three papers = 100 + 100 + 100 = 300

∴ Percentage of marks = `("Total secured marks "/"Total marks") xx 100%`

= `(53 + 75 + x)/300 xx 100%`

But it is given that he obtained over all of 70% marks

∴ `(53 + 75 + x)/300 xx 100` = 70

⇒ `(128 + x)/3` = 70

⇒ 128 + x = 210

⇒ 210 – 128

∴ x = 82

Hence, he must secure 82 marks in the third paper to get an overall of 70% marks.