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
Every question was attempted, so correct answers + wrong answers = 200. The marks are 4 for each correct answer minus 1 for each wrong one.
The marks (4 for each of the \(c\) correct answers, less 1 for each of the \(200-c\) wrong ones):
Correct answers \(=c\), wrong answers \(=200-c\)
Marks: \(4c-(200-c)=200\)
Finding \(c\):
\(5c-200=200\)
\(5c=400\), so \(c=80\)