• # question_answer If answer to all questions be attempted by guessing were wrong, then how many questions answered correctly to score 90 marks? A) 24 B) 70 C) 96 D) 100

 Let number of questions be answered correctly be x. Then, Number of questions be answered by giving $=(120-x)$. So.    $x\times 1+(120-x)\times \left( -\frac{1}{4} \right)=90$ $\Rightarrow \,\,\,\,\,\,\,\,\,\,4x-(120-x)=380$ $\Rightarrow \,\,\,\,\,\,\,\,\,\,5x=380+120=500$ $\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=100$ Hence, he answered 100 answer correctly. So option [d] is correct.