(Original post by justinawe)
I'll try and explain this as clearly as I can.
So, you get 4 marks for a correct answer, lose 2 marks for a wrong answer and lose 1 mark for an unattempted question, yes? To find the total mark, you would take the number of correct answers multiplied by 4 and subtract the number of wrong answers multiplied by 2 as well as the number of unattempted questions.
The question says that a candidate gets
number of questions correct. So, to find out how many marks the candidate gets from correct answers, we multiply this by 4, giving
Now, we know that the candidate attempts
questions and gets
correct. If we subtract the number of correctly answered questions from the total number of attempted question, we would get the number of questions the candidate answered wrong. So, we can say that the candidate got
questions wrong. To find out how many marks were deducted due to wrong answers, we multiply this by 2. Giving
There are 25 questions in the examination, the candidate attempted
questions. So, there would be
unattempted questions, and also
marks deducted as it's 1 mark deducted for every unattempted question.
Simplify this, and you have your expression!
Since you say you're fine with algebra, I assume you'll be able to do part (ii) on your own now. Quote me of you've got any problems.