SOLUTION: In an examination a student scores 1 mark for each correct answer and 0.25marks are deducted for each wrong answer. If he attempts all 120 questions and secures 90 marks the number

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Question 751963: In an examination a student scores 1 mark for each correct answer and 0.25marks are deducted for each wrong answer. If he attempts all 120 questions and secures 90 marks the number of question he attempts correctly is?
Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
Assuming 90 marks is a score (and not a percentage)
R-right answers
W-wrong
Total questions: R+W=120
Score: R-0.25W=90

System
R+W=120
R-0.25W=90

Subtracting equations leads to
(R+W)-(R-0.25W)=120-90
then
1.25W=30
W=24
so that R=120-24=96

96 correct


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