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Ratio problem
http://www2.elevenplusexams.co.uk/forum/11plus/viewtopic.php?f=2&t=56696
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Author:  Erijkhan [ Mon Nov 26, 2018 1:12 pm ]
Post subject:  Ratio problem

If one cake and two biscuits provide 450 calories and two
cakes and three biscuits provide 800 calories, how many
calories are provided by one biscuit?

How to solve this problem, please?

Author:  anotherdad [ Mon Nov 26, 2018 1:43 pm ]
Post subject:  Re: Ratio problem

How old is the child tackling the problem? I know how I'd do it but it might not be appropriate for someone in say, year 5.

Author:  Erijkhan [ Mon Nov 26, 2018 1:45 pm ]
Post subject:  Re: Ratio problem

9 years old.

Author:  anotherdad [ Mon Nov 26, 2018 1:46 pm ]
Post subject:  Re: Ratio problem

In which case I'll leave it to the maths teachers on here because I may end up confusing the situation. I suspect my method won't have been covered in school yet.

Author:  RedPanda [ Mon Nov 26, 2018 1:50 pm ]
Post subject:  Re: Ratio problem

Hi Erijhkan - Is this for an 11+?

Anyway, can you work out how many calories there are in 1 cake and 1 biscuit? Hint: look at the difference between the facts you have been given.

From there you can compare 1 cake and 1 biscuit with 1 cake and 2 biscuits. The difference will be the extra biscuit.

Edit: Crossed post with anotherdad. I suspect this is beyond KS2. Guest will know for sure.

Author:  Erijkhan [ Mon Nov 26, 2018 1:58 pm ]
Post subject:  Re: Ratio problem

Thanks for your reply. it is helpful.

Yes, this is for 11+, from one of the grammar school paper.

Author:  Guest55 [ Mon Nov 26, 2018 2:02 pm ]
Post subject:  Re: Ratio problem

Erijkhan wrote:
If one cake and two biscuits provide 450 calories and two cakes and three biscuits provide 800 calories, how many calories are provided by one biscuit?

This is not a Year 5 question.

one cake and two biscuits provide 450 calories
two cakes and three biscuits provide 800 calories

The difference between these two sentences tells us that one cake and one biscuit provide 350 calories.

Now compare to the first sentence - the 'extra' biscuit must be 100 calories.

{It is not appropriate to try and use algebra for these}

Author:  Reading Mum [ Mon Nov 26, 2018 2:05 pm ]
Post subject:  Re: Ratio problem

Erijkhan wrote:
If one cake and two biscuits provide 450 calories and two
cakes and three biscuits provide 800 calories, how many
calories are provided by one biscuit?

How to solve this problem, please?


you know:
1c + 2b = 450
2c + 3b = 800

therefore, from the first fact
2c + 4b = 900 (by doubling)

therefore the diff is 1b so 1b = 100

Author:  Guest55 [ Mon Nov 26, 2018 2:07 pm ]
Post subject:  Re: Ratio problem

Reading mum - algebra is not appropriate or needed here.

Author:  Reading Mum [ Mon Nov 26, 2018 2:08 pm ]
Post subject:  Re: Ratio problem

its the only way I know, and how my DD would have done it (probably related to the first point)

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