Impossible Maths Question Aimed At 10 Year Olds?

[fiction-factory]

http://www.mirror.co.uk/news/uk-news/simple-maths-exam-question-10-8132599

The Dad said he has A levels and spent an hour trying to solve it before saying he couldn't solve it. He said friends who were maths teachers or had a first class degree couldn't solve it.

[Prudie]

I saw this too, I can convince myself that by shifting the right hand vertical to the right and horizontal up to fill the space then it was a 10x12 rectangle (although not drawn to the right proportions) making the perimeter 44 but the bottom one I couldn't quite apply the same logic. How about you?

[atalanta]

Not enough information, and shapes drawn out of proportion.

[Fibonacci]

The second shape: if 2cm is the small vertical measurement.
Perimeter will be 9+11+9+11+2+2 = 44cm

[zebo]

The first one was easy, the indent can be ignored, it's still the same length and width, so it's 12 x 10 which is 44 cm, 2 x 22. The second is slightly harder as the indents reverse direction, but taking the 2 as referring to the height of the indent, then it too is 44cm, 9 x 11 which has perimeter of 2 x 20 = 40, but the extra 2cm is covered twice, hence it's 40 + 2 + 2=44cm.
In any exam the questions are to test a range of abilities, the second part will weed out the most able.
I used to tell my pupils that if a multi-part question seemed to repetitious, look again, the later parts will be more tricky.

[Prudie]

See I read the 2cm as the horizontal measurement, as would many. That shouldn't be left to speculation in order to make an answer achievable.

[mikey4444]

I can't see how anybody could be exact. In the 1st example, we are not told the height and length of the little sticky-out bit on the right !

[Jackdaw33]

This has got to be a spoof. You don't use words like ''composite rectilinear' when talking to 10-year-olds.

[mikey4444]

Jack....I am 63 years old, and I have NEVER used ''composite rectilinear' in my entire life, nor seen the reason to do so !

I agree though....this doesn't make any sense whatsoever, with important measurements being left out....a misprint perhaps ?

[Jackdaw33]

I know what rectilinear means and I know what composite means but when conjoined I'm baffled.

[fiction-factory]

Mikey, all the measurements you need are there.

The first one is 44cm. It doesn't matter what the missing lengths are- the vertical bits have to add to 24 and the horozontal bits add to 20cm.

On the second one the problem is that it isn't clear which bit the 2 cm figure refers to. It has to be the vertical bit though because that will give only one possible answer- 44cm, whereas if the 2cm was for the horizontal length then the are loads of (infinite) solutions.

[fiction-factory]

Thanks for all the answers. Although the dad who went public with statement that both questions were impossible may now be feeling a bit embarrassed, I expect it has helped him remember how to tackle problems in a logical way and made him better able to help his children with homework in future.

Whilst I cannot see any catch in the first question i can see that for Q2 , even if it were made clear that the 2 cm length referred to the vertical section, it is not a straightforward question. I think many GCSE pupils would also struggle, as it doesn't follow the usual format of these questions and requires a bit more thinking or algebra or trial and error than is usually the case with perimeter questions.

[Jackdaw33]

Can I repeat: This question is aimed at 10 year-olds using words like composite and rectilinear. Someone's having a laugh.

[fiction-factory]

You can but that wasn't my question.

[fiction-factory]

10 year olds will be/should be familiar with the term compound rather than composite
I doubt I would ever say rectlinear

[jno]

if they've been taught what composite rectilinear means, they'll know; it doesn't matter that their grandparents don't.

If they haven't been taught it, they probably won't and either teachers or examiners should be doing some explaining.

But the second one is ambiguous.

[fiction-factory]

Actually, I have used this Primary School worksheet and it does use the term
rectilinear. I think it's more likely to be found on US worksheets


http://www.math-salamanders.com/perimeter-worksheets.html

[zebo]

Thanks for the BA! As an escaped Maths teacher, I've never used the phrase composite rectilinear, most pupils' eyes would glaze over at the phrase but it is in the current curriculum for KS2 so they may know it and a bright 10 year old should be able to think round the problem. As an aside, my 10 year old granddaughter was doing her weekend spellings recently, one of which was 'absurdance', a word I've never heard, it's got the red underlining as I write. There seems to be a desire to improve standards by introducing the most ridiculous language, what's wrong with absurdity?
One of my favourite language experiences from teaching was a lad who referred casually to hypotenuse as Harry Potter's pubes, I chuckled every year I taught it after that!