Question

There are 48 questions in a test. Each correct answer fetches 1 mark, for each wrong answer
marks is deducted. A student got 21 marks and he attempted all the questions. Find the number of questions he answered wrongly
(A) 28
(B) 8
(C) 12
(D) 18
​

Answer 1

By assumption method, 

If, he answered 30 questions correctly, then he will get 30 marks for it.

And, the remaining questions answered were incorrect, i.e. 18.

Therefore 9 marks will be deducted from the secured marks. (Since, 18/2 = 9)  

So, the equation gets correct and we get the final marks scored to be 21 as in the question.

Therefore, 18 questions were answered incorrect.

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