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North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 3:21 pm
by leanmeamum
Question 38 - Can anyone help with this question?

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 3:24 pm
by Guest55
Can you type it out?

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 3:33 pm
by leanmeamum
Sorry - it is copied out below.

Magda and her friends go to the cinema.
They buy 1 large tub of popcorn, 4 fizzy drinks and 10 packets of crisps. The bill comes to £10.89.

Lena and her friends go to the cinema.
They buy 1 large tub of popcorn, 3 fizzy drinks and 7 packets of crisps. The bill comes to £8.64.

How much would it cost to buy 1 large tub of popcorn, 1 fizzy drink and 1 packet of crisps?

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 3:51 pm
by Guest55
What is the answer?

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 3:53 pm
by leanmeamum
don't know - tried simultaneous equations and ratios but am stumped.

There seems to be some information missing unless I'm missing something really obvious and being tunnel visioned which is why I hope someone will come along and solve the riddle

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 3:59 pm
by Guest55
Well this is what I did ...

I subtracted to get what one fizzy drink and 3 packets of crisps is.

Then I rewrote the first as:

1 large tub of popcorn + 1 fizzy drink + 1 packet of crisps + (3 fizzy drinks and 9 packets of crisps) is 10.89

Does that help?

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 4:12 pm
by leanmeamum
Thank You - quite neat although would a 10/11 year old know how to expand an equation.

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 4:22 pm
by Guest55
I think it's a bit tricky but it doesn't need algebra.

The key is understanding that you don't need the individual price of each thing.

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 5:52 pm
by future
DS has worked it out as follows

1P + 4D + 10C = £10.89
1P + 3D + 7C = £8.64
1D + 3C = £2.25
3D + 9C = £6.75

£10.89 - £6.75 = £4.14

Hope this helps.

Re: North London Consortium 2013 Group 2

Posted: Sat Jan 04, 2014 6:00 pm
by Guest55
Future that's what I did without the need for algebra!