Q94
ArithmeticNumber System, LCM/HCF & Divisibility
There are 75 questions in a question paper each carrying 2 marks. 1 mark is deducted for each question answered incorrectly. A student answering all the questions got 45 marks. What is the number of questions correctly answered by the student?
- a.42
- b.41
- c.45
- d.40
Answer: (D) 40
Let the number of correct answers be $x$; then wrong answers $=75-x$, since all questions were attempted. Marks: $2x-(75-x)=45$, so $3x=120$ and $x=40$. Check: $40\times2-35\times1=80-35=45$. Shortcut: if all 75 were right the score would be 150; each wrong answer costs 3 marks (2 lost + 1 deducted), so the number of wrong answers is $(150-45)\div3=35$, leaving 40 right.