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 Post subject: coin problem
PostPosted: Wed Aug 28, 2013 10:05 pm 
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Joined: Wed Aug 28, 2013 9:53 pm
Posts: 3
Hi

Please can anyone help me with this problem. i think it is a ratio problem which for the life of me i cannot work out.

A cash box contains some coins to the value of £5.25.
There are twice as many 5p coins as 2p coins, and twice as many 2p coins as 1p coins.

This means there are:
1. how many 5p coins
2. how many 2p coins
3. how many 1p coins

Please help. :?


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 Post subject: Re: Maths
PostPosted: Wed Aug 28, 2013 10:17 pm 
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Joined: Fri Oct 12, 2007 12:42 pm
Posts: 3810
Location: Chelmsford and pleased
Think how much money is made from one set of the coins.

1p + 4p (2, 2p - 2 x no. of 1p) + 20p (4, 5p - 2 x no. of 2p coins) = 25p

How many 25p in £5.25? 21

So 21 1p coins is 21p
42 2p coins is 84p and
84 5p coins is 420p

Check
21 + 84 + 420 = 525


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 Post subject: Re: Maths
PostPosted: Wed Aug 28, 2013 10:30 pm 
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Joined: Wed Aug 28, 2013 9:53 pm
Posts: 3
Thanks, however i am trying to teach this to a 10 year old and really need to break it down to him. Please if possible could you break it down further for me as i am still very confused. I am really useless at maths. sorry


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 Post subject: Re: Maths
PostPosted: Wed Aug 28, 2013 10:45 pm 
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Joined: Fri Oct 12, 2007 12:42 pm
Posts: 3810
Location: Chelmsford and pleased
I taught ratio by drawing beads.

I would start with that.

green bead costs 1p
red bead costs 2p
blue bead costs 5p

For every green bead there are two red beads.

GRR

For every red bead there are two blue beads, so your bracelet has this pattern.

GRRBBBB
1+2+2+5+5+5+5

The cost of these beads is: 1p + 4p + 20p = 25p

How many sets of GRRBBBB can you buy for £5.25. The answer is 21 (525/25)
So your bracelet has
21 G
42 R and
84 B.


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 Post subject: Re: Maths
PostPosted: Wed Aug 28, 2013 11:13 pm 
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Joined: Sat Jan 12, 2013 10:02 pm
Posts: 88
kentlady wrote:
Hi

Please can anyone help me with this problem. i think it is a ratio problem which for the life of me i cannot work out.

A cash box contains some coins to the value of £5.25.
There are twice as many 5p coins as 2p coins, and twice as many 2p coins as 1p coins.

This means there are:
1. how many 5p coins
2. how many 2p coins
3. how many 1p coins

Please help. :?


*If there are two 5p coins then there is one 2p coin (the ratio is 2:1)
*If there are two 2p coins then there is one 1p coin (the ratio is 2:1)

Which can also be rewritten as:

*If there are four 5p coins, then there are two 2p coins and one 1p coin (the ratio is 4:2:1, we are taking all the coins into account to form a ratio)

*If we write this in the form of an equation it will be like this:

4(5p) + 2(2p) + 1(1p) = 20p + 4p + 1p = 25p

*Now that you know that this gives you 25p you have to do:

5.25/0.25 = 21

*This means the following equation occurs 21 times:

4(5p) + 2(2p) + 1(1p) = 20p + 4p + 1p = 25p

*Therefore there are:

21 x 4(5p) = 84 x 5p coins
21 x 2(2p) = 42 x 2p coins
21 x 1(1p) = 21 x 1p coins

(84 x 5) + (42 x 2) + (21 x 2) = 525p


Last edited by Rainbow Petals on Thu Aug 29, 2013 10:28 am, edited 1 time in total.

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 Post subject: Re: Maths
PostPosted: Wed Aug 28, 2013 11:29 pm 
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Joined: Wed Aug 28, 2013 9:53 pm
Posts: 3
Thanks so much, got it. Much appreciated.


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