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 Post subject: ratio question
PostPosted: Wed Aug 15, 2012 6:56 pm 
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Joined: Wed Aug 15, 2012 6:49 pm
Posts: 1
Dear Maths man,

Please can you explain the following question's answer in detail.

A bag contains One pence and Two pence coins to the value of £5.28. There are Five times as many Two pence coins as One pence coins. How many 1 pence coins are there in the bag?


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 Post subject: Re: ratio question
PostPosted: Wed Aug 15, 2012 7:00 pm 
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Joined: Mon Aug 22, 2011 8:20 pm
Posts: 1706
Location: Warwickshire
5 x 2p coin + 1 x 1p coin = 11p
i.e. for every 11p value there will be one 1p coin.

Divide £5.28 by 11 gives 48.

Therefore 48 x 1p coins


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 Post subject: Re: ratio question
PostPosted: Wed Aug 15, 2012 7:04 pm 
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Joined: Mon Feb 12, 2007 1:21 pm
Posts: 11934
Maths lady here!

If there are 5 x the number of 2p then the 2p conis make a multiple of 10p. This means the '8' at the end comes from the 1p coins and these must therefore be a multiple of 8.

Trial and improvement

8 1p 40 2p we know this isn't enought to make £5 plus

16 1p 80 2p ditto

48 1p 240 2p will give £5.28


No need for algebra because you know most of the money is 2p coins and the number has to be a multiple of 40 ...


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 Post subject: Re: ratio question
PostPosted: Fri Aug 17, 2012 7:51 am 
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Joined: Wed Aug 01, 2007 11:19 am
Posts: 888
Doesn't the 8 at the end mean the 1p's must come in an amount that ends in 8? 8, 18, 28, etc? 16 Pennies would give you an amount ending in 6.

If I were explaining that question to someone, I would use Okanagan's method I think, as it seems easier to me to visualise what's going on - imagine one penny, so that must have five 2p's with it. So how much in that pile? And then how many piles would you need?


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