11 Plus Exams Forum
https://www.elevenplusexams.co.uk/forum/11plus/

Simultaneous Equations Questions
https://www.elevenplusexams.co.uk/forum/11plus/viewtopic.php?f=2&t=54496
Page 1 of 6

Author:  RedDevil66 [ Tue May 22, 2018 8:29 am ]
Post subject:  Simultaneous Equations Questions

Some of you may know the type.
EG.
Andrew paid £12 for 4 cups of coffee
and 4 cups of tea. 3 cups of coffee
cost as much as 2 cups of tea.
What was the total cost of 5 cups of
tea and 5 cups of coffee?.

Is there any good practice for this type of question online or in a book?

PS: I do know the answer and how to work it out :wink:
The total cost of 5 cups of coffee and 5 cups of tea was £15

Author:  Surferfish [ Tue May 22, 2018 9:44 am ]
Post subject:  Re: Simultaneous Equations Questions

I don't think you even need to know the second piece of information to work out the answer.

If 4c + 4t = 12

then c + t = 3.

So 5c + 5t = 15.

So in one sense its quite straightforward, but in another sense its a bit tricky because the question includes unnecessary information (that 3 cups of coffee costs the same as 2 cups of tea) and its natural to assume that you need to use this to work out the answer and to try and include it in your calculation.

Author:  Guest55 [ Tue May 22, 2018 9:45 am ]
Post subject:  Re: Simultaneous Equations Questions

Make them up? They need no algebra to find the answer ...

Author:  Guest55 [ Tue May 22, 2018 9:50 am ]
Post subject:  Re: Simultaneous Equations Questions

Surferfish wrote:
I don't think you even need to know the second piece of information to work out the answer.

If 4c + 4t = 12

then c + t = 3.

So 5c + 5t = 15.

Please don't use algebra for this type - it's not needed.

Author:  Surferfish [ Tue May 22, 2018 9:55 am ]
Post subject:  Re: Simultaneous Equations Questions

Guest55 wrote:
Surferfish wrote:
I don't think you even need to know the second piece of information to work out the answer.

If 4c + 4t = 12

then c + t = 3.

So 5c + 5t = 15.

Please don't use algebra for this type - it's not needed.


How would you work out the answer then?

Author:  Guest55 [ Tue May 22, 2018 10:01 am ]
Post subject:  Re: Simultaneous Equations Questions

You use your brain and note that the total of each item is the same.

"3 ice creams and 4 lollies cost £5

6 ice creams and 5 lollies cost £8.50

How much does it cost to buy an ice cream and a lolly?"

We can see we are buying 9 of each. This costs £13.50 so one of each costs £1.50.

Author:  stroudydad [ Tue May 22, 2018 10:06 am ]
Post subject:  Re: Simultaneous Equations Questions

Guest55 wrote:
You use your brain and note that the total of each item is the same.

"3 ice creams and 4 lollies cost £5

6 ice creams and 5 lollies cost £8.50

How much does it cost to buy an ice cream and a lolly?"

We can see we are buying 9 of each. This costs £13.50 so one of each costs £1.50.


With the greatest of respect I think this confuses the OP. This is different to the question that was asked, because in the OP the cost of tea and coffee is not the same..

Edit.... though I do agree that it is quite simple arithmetic that tea plus coffee is £3 so no algebra is required.

Author:  Surferfish [ Tue May 22, 2018 10:14 am ]
Post subject:  Re: Simultaneous Equations Questions

Guest55 wrote:
You use your brain and note that the total of each item is the same.

"3 ice creams and 4 lollies cost £5

6 ice creams and 5 lollies cost £8.50

How much does it cost to buy an ice cream and a lolly?"

We can see we are buying 9 of each. This costs £13.50 so one of each costs £1.50.


But that is exactly the same as the way I did it.

The "algebra" is just a neat, shorthand way of writing down the thought process which you went through and described in English words.

Author:  stroudydad [ Tue May 22, 2018 10:47 am ]
Post subject:  Re: Simultaneous Equations Questions

Surferfish wrote:
Guest55 wrote:
You use your brain and note that the total of each item is the same.

"3 ice creams and 4 lollies cost £5

6 ice creams and 5 lollies cost £8.50

How much does it cost to buy an ice cream and a lolly?"

We can see we are buying 9 of each. This costs £13.50 so one of each costs £1.50.


But that is exactly the same as the way I did it.

The "algebra" is just a neat, shorthand way of writing down the thought process which you went through and described in English words.


Perhaps G55 was referring to the OP which referenced simultaneous equations. :-)

Author:  Guest55 [ Tue May 22, 2018 10:50 am ]
Post subject:  Re: Simultaneous Equations Questions

Surferfish wrote:
But that is exactly the same as the way I did it.

The "algebra" is just a neat, shorthand way of writing down the thought process which you went through and described in English words.


With respect, it is not - you introduced notation which was unnecessary and I'd mark it wrong as you did not define your variables.

Page 1 of 6 All times are UTC [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/