In an objective examination of 90 questions, 5 marks are allotted for every correct answer and 2 marks are deducted for every wrong answer. After attempting all the 90 questions a student got a total of 387 marks. Find the number of questions that he attempted wrong
Let the number of correct answers be C and wrong answers be W.
C + W = 90Â Â ---(1)
5C - 2W = 387Â Â ---(2)
Multiplying equation 1 by 5 and then subtracting, we get
7W = 450 - 387 = 63
W = 9
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