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.
Answer
Answer (as printed):
Explanation
Let the number of questions attempted correctly be x. Then, number of questions attempted wrong = (90 – x) \ 5x – 2(90 – x) = 387 ⇔ 7x = 387 + 180 = 567 ⇔ x = 81. Hence, number of questions attempted wrong = (90 – 81) = 9.
Explanation as extracted from the printed page; notation may be imperfect.