In an examination, you have to answer 100 questions and for each wrong answer, there will be a cut 0.4 mark from your actual marks.and your results say you get 65 marks, so how many wrong answers do you have?

Note:we get 1 mark for each right answer.

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## Comments

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TopNewestAssuming we get 1 mark for each right answer before deduction, and let the number of questions wrongly answered be $x$. Then we have

$\begin{aligned} (100-x)-0.4x & =65 \\ 1.4x & = 35 \\ \implies x & = 25 \end{aligned}$

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@Chew-Seong Cheong Thanks a lot,now I understand it and If we say "we get 2 marks for each right answer" then the result of the number of questions wrongly answered will stay the same?I think the mark for each right answer is not necessary to know to get the amount of wrong answers

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200-x-0.4x=65, 135=1.4x. x is not a whole number, meaning that x does matter

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$x$? amount of right answers or amount of wrong answers?

For 2 marks for each right answer, 200 is marks not the amount of question.and what do you mean byLog in to reply

$2(100-x)-0.4x = 65$. Then $x=56/25$

It should beLog in to reply

$x=135/2.4=56.25$

I meanLog in to reply

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What is the mark for each correct answer?

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I've edited that "we get 1 mark for each right answer." although I think the mark for each right answer is not necessary to know to get the amount of wrong answers.

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@Calvin Lin @Pi Han Goh @Chew-Seong Cheong

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What have you tried? Where are you stuck?

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I was stuck at the beginning,didn't know how to start.

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