Question

there are 48 questions in a test. each correct answer fetches 1 mark , for each wrong answer ½ is deducted . A student got 21 marks by attempting ask questions. The number of questions answered wrongly is?

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.

Hope this answer helps you

Answer 2

Answer:

the answer is 18

Step-by-step explanation:

according to question

each correct answer fetches 1 mark and each wrong answer fetches -1/2 marks

so if thought for a moment you'll get to know that each wrong answer also carries away his 1 mark which he would have got by answering correctly so each wrong answer deducts 3/2 marks and he got 21 marks which means his 27 marks was deducted

NOW:---

NO OF WRONG ANSWERS ---

27÷3/2=18

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