In a competitive examination 1 mark is awarded for a correct answer, 0 marks for an unattempt question and \(\frac{1}{2}\) mark is deducted for every wrong answer. Ambika answered 120 questions and got 90 marks. How many answers were correct?
In a competitive examination 1 mark is awarded for a correct answer, 0 marks for an unattempt question and \(\frac{1}{2}\) mark is deducted for every wrong answer. Ambika answered 120 questions and got 90 marks. How many answers were correct? Correct Answer 100
Given:
Number of question attempted = 120
Marks received by Ambika = 90
Marks awarded for correct answer = 1
Marks deducted for wrong answer = 0.5
Calculation:
Let the number of correct answer be = a
⇒ Number of wrong answers = 120 - a
Marks for 'a' right answers = a × 1 = a
Marks deducted for (120 - a) wrong answers = (120 - a) × 0.5 = 60 - 0.5a
As per the question;
Total marks scored = Marks received for right answers - Marks deducted for wrong answers
⇒ 90 = a - (60 - 0.5a)
⇒ 1.5a = 150
⇒ a = 100
∴ The number of correct answers is 100.