In an examination, a student scores 4 marks for every correct answer and loses 1 mark for every wrong answer. A student attempted all the 200 questions and scored in all 200 marks. The number of questions he answered correctly was
(a)60
(b)68
(c)80
(d)82
Answer
Answer (as printed): C
Explanation
Let the number of questions answered correctly be $x$. Then, number of wrong answers $=(200-x)$. $\therefore \quad 4 x-(200-x)=200 \Rightarrow 5 x=400 \Rightarrow x=80$.
Explanation as extracted from the printed page; notation may be imperfect.