Question

in a competitive exam 1 mark is for correct answer and 1/2 mark is reduced for wrong if jai answered 120 questions and got 90 marks find how many answers were correct and how many answers were wrong​

Answer 1

Step-by-step explanation:

Total answers = 120

Let the number of correct answers = x

number of wrong answers = (120-x)

Marks awarded for each right answer = 1

then Marks awarded for x right answer = x × 1 = x marks

Marks deducted for each wrong answer = 0.5

then marks deducted for (120-x) right answers = (120-x) × 0.5 = 60 - 0.5x

So he will get= marks awarded for right answer - marks deducted for wrong answer

                    = x - (60-0.5x)

                    = x - 60 + 0.5x

                    = 1.5x - 60

And he has got = 90 marks

So

1.5x - 60 = 90

⇒ 1.5x = 90 + 60

⇒ 1.5x = 150

⇒ x = 150/1.5 

⇒ x = 100

So he did 100 questions correctly.

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