In a competitive examination, 5 marks are awarded for each correct answer, while 2 marks are deducted for each wrong answer. Jayant answered 120 questions and got 348 marks. How many questions did he answer correctly?
Let the number of correct answers = x
Let the number of wrong answers = y
Total no of questions attempted = x + y = 120
⇒ y = 120 - x ….[1]
Marks for each correct answer = 5
Marks for x correct answers = 5x
As 2 marks are deducted for each wrong question,
Marks deducted for y wrong answers = 2y
Total marks obtained by student will be 5x - 2y,
⇒ 5x - 2y = 348
⇒ 5x - 2(120 - x) = 348
⇒ 5x - 240 + 2x = 348
⇒ 7x = 588
⇒ x = 84
Hence, no of correct answers = x = 84