# Maths question for 13 year old

warpig3 | 08:29 Tue 19th Feb 2008 | Science
Sorry, not really science but didn't know were else to post.

I was going through a maths paper with my friends daughter yesterday and she got the following question:

'Some children are going to a fun park and the teacher wants to know how much the trip will cost. The bus hire is �120, the cost of entry per pupil is �15.

The total cost is calculated as follows:

Total cost = bus hire + no of pupils x entry fee per pupil

How much will it cost in total to take 20 children?'

I have typed the formula exactly the way it was written on the paper. My question is, would you expect children to suss that the formula is written incorrectly, is that something they are being tested for, or if they got the answer wrong by applying the formula as stated should they in fact be marked right?

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Since, in the absence of brackets, multiplication should be performed before addition, the formula as written will give the correct answer. It would be clearer to place brackets around the no of pupils x entry fee per pupil statement or to
turn the equation round so that this becomes the start of the calculation. Presumably, however, this was part of the reason for setting such an apparently easy question to a class of 13 year olds, to test whether they understood the reasons for what they were doing or just simply going through the motions.
Question Author
Good point dundurn, I completely forgot about multiplying before addition, mind you its a long time since I had to think about it.
The order of operations is taught in schools at about that age.

I can't recall the way they're taught to remember it now but when I was at school it was BODMAS

Brackets Of Division Multiplication Addition Subtraction
Question Author
Thanks JTP, I will pass that on to her, it was only common sense that enabled me to get the right answer!
A tip to remember order of operations:

Please Excuse My Dear Aunt Sally (PEMDAS)
Parenthesis, Exponents, Multiplication, Division, Addition, Subtraction
I went to a slightly less upmarket school. We couldn't afford parentheses or exponents and we learnt to �Bless My Dear Aunt Sally� (Brackets, Multiply, Divide, Add, Subtract).

It seems quite outrageous now that we led such deprived childhoods, but it didn�t do me any harm!
Similarly we were taught BIDMAS! Same as Jakes answer but with Indices instead of Of

My mum was taught Bodmas though!
This is one of the reasons I have no maths qualifications - I have never heard of any of these mnemonics.
420 pounds
420

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