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Maths help!

2662857

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How would I answer this question???

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Reply 1

theBranicAc

Original post by Jack_Tomlin

Here is the link to a screenshot of the question. http://prntscr.com/bnu0g7

How would I answer this question???

I did this question in my gcse maths(9-1) mock!!

Its a fairly easy question, what you have to do is work out how many literes of water he uses in a year, find how much that is cubic meteres. Then times this by 0.9122 to find out how much it cost a year for using water. Add this to the amount of 28.20 and compare which one is cheaper

Reply 2

Kevin De Bruyne

Original post by Jack_Tomlin

Here is the link to a screenshot of the question. http://prntscr.com/bnu0g7

How would I answer this question???

What have you tried? :h:

Reply 3

B_9710

Work out how many litres he uses per year.

Reply 4

2662857

Original post by theBranicAc

Could you do a solution for it please? So what do i times 180 by? I don't know how I would convert litres to cubic litres

Reply 5

B_9710

Original post by Jack_Tomlin

Could you do a solution for it please? So what do i times 180 by? I don't know how I would convert litres to cubic litres

It gives you the conversion factor.

Reply 6

2662857

Original post by B_9710

It gives you the conversion factor.

So how would i convert 180 litres to cubic metres?

Reply 7

theBranicAc

Original post by Jack_Tomlin

Could you do a solution for it please? So what do i times 180 by? I don't know how I would convert litres to cubic litres

Times 180 by 365-> this gives the amount of literes in a year
Divide it by 1000, to find the out how much cubic meteres it is

Reply 8

2662857

Original post by theBranicAc

Times 180 by 365-> this gives the amount of literes in a year
Divide it by 1000, to find the out how much cubic meteres it is

Ok understand the first bit because he uses 180 litres a day and there is 365 days in a year (180 x 365 = 65700 litres)

I don't understand why you divide it by 1000?
Sorry

Reply 9

TheCe

Original post by Jack_Tomlin

Ok understand the first bit because he uses 180 litres a day and there is 365 days in a year (180 x 365 = 65700 litres)

I don't understand why you divide it by 1000?
Sorry

Because 1 cubic metre= 1000 litres

Reply 10

2662857

Original post by TheCe

Because 1 cubic metre= 1000 litres

Still doesnt make sense dw :frown:

Reply 11

TheCe

Original post by Jack_Tomlin

Still doesnt make sense dw :frown:

You know the unitary method?

Reply 12

2662857

Original post by TheCe

You know the unitary method?

nope

Reply 13

theBranicAc

Original post by Jack_Tomlin

Still doesnt make sense dw :frown:

How are you doing the higher tier if you dont know basics like the unitairy method

Reply 14

TheCe

Original post by Jack_Tomlin

nope

Well say:-
1000 litres = 1 cubic metre
then 180 litres = x cubic metres
now cross multiply
1000x = 180
x = 180/1000

Does it make sense now?

Reply 15

2662857

Original post by theBranicAc

How are you doing the higher tier if you dont know basics like the unitairy method

Im not doing the higher tier this was from the foundation specimen papers

Reply 16

2662857

Original post by TheCe

Well say:-
1000 litres = 1 cubic metre
then 180 litres = x cubic metres
now cross multiply
1000x = 180
x = 180/1000

Does it make sense now?

Is it because to get from 1000 to 1 cubic metre you divide by 1000 to cancel the 4 zeros?

Reply 17

Rather_Cynical

If it helps, you can rewrite your equations with all the units in.

1000L = 1m³, so that's 1000L per m³.
To cancel the units, 180L per day/1000L per m³ gives you 9/50 m³ per day.
Now use these figures to work out cubic meters per year, hence find the cost per year.

Reply 18

TheCe

Original post by Jack_Tomlin

Is it because to get from 1000 to 1 cubic metre you divide by 1000 to cancel the 4 zeros?

If it makes it easier for you to understand, then yeah take it that way.

But a better approach would be using the unitary method.
Or you can look at it this way. We know a cubic metre is a larger quantity than a litre, since only 1 cubic metre is equal to a 1000 litres.
In such a case, as in when converting from a larger quantity to a smaller quantity, you divide.
And when converting from a smaller quantity to a larger quantity, you multiply.

Does this help?

Reply 19