Question:
In an examination, a candidate scores 4 marks for every correct answer and loses 1 mark for every wrong answer. If the attempts all 100 questions and secures 100 marks, the number of questions he attempts correctly is:
A30
B50
C45
D40
Answer:
D. 40
Explanation:
Let the correct answers = x No of wrong answer = y x+y=100 => (1) 4x-y=100 => (2) (1)+(2), 5x = 200 X = 40.