In an examination a pupil's average marks were 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his History paper, his average per paper would have been 64. How many papers were there in the examination?  Select
A) 8	B) 9	C) 10	D) 22	E) 12
Let the number of papers be x. Then,   63x + 20 + 2 = 64x   = x = 22   ANSWER:22
<result>D</result>
In an examination a pupil's average marks were 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his History paper, his average per paper would have been 64. How many papers were there in the examination?