In an examination which had 200 questions, students score 4 marks for every correct answer and lose 1 mark for every wrong answer.
A student attempted all the 200 questions and scored 200 marks. The number of questions, student answered correctly in the examination, is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 80
Let the number of correct answers = $x$
Then number of wrong answers = $200 – x$
Scoring rule:
- Correct answer → +4
- Wrong answer → −1
Total score = 200
$4x - 1(200 - x) = 200$
$4x - 200 + x = 200$
$5x - 200 = 200$
$5x = 400$
$x = 80$