Maths experts please!
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Maths experts please!
Can someone (Guest 55?!) please help with a method for the following question:
1G + 2M = £2.80
2G + 5M = £6.10
Find the value of 1G and 1M.
I'm totally stumped and memories of struggling with maths are flooding back. I've poured myself a glass of wine, but that's not helping!
Any help would be very gratefully received
Jess
1G + 2M = £2.80
2G + 5M = £6.10
Find the value of 1G and 1M.
I'm totally stumped and memories of struggling with maths are flooding back. I've poured myself a glass of wine, but that's not helping!
Any help would be very gratefully received
Jess
poss..
Dont you multiply one so that tehre is an equal number of one of the unknowns?
ie 1G + 2M = £2.80
times 2 = 2G+4M = £5.60
then take one from the other....
2G + 5M = £6.10 minus 2G+4M = £5.60
leaving
1M = 50p
therefore
1G would be £1.80 (substituting into 1G +2M=£2.80)
maybe...havent checked....check later...something burning in oven
Dont you multiply one so that tehre is an equal number of one of the unknowns?
ie 1G + 2M = £2.80
times 2 = 2G+4M = £5.60
then take one from the other....
2G + 5M = £6.10 minus 2G+4M = £5.60
leaving
1M = 50p
therefore
1G would be £1.80 (substituting into 1G +2M=£2.80)
maybe...havent checked....check later...something burning in oven
1G + 2M = £2.80
2G + 5M = £6.10 [note there really should NOT be £ signs in the question]
Yes - we need the same number of Gs or Ms so
1G + 2M = £2.80 (x2) 2G + 4M = £5.60
2G + 5M = £6.10 (x1) 2G + 5M = £6.10
so M = £0.50 or 50p
back in our first equation,
1G + 1 = £2.80
so G = £1.80 now check in the other equation: 3.60 + 2.50 does give 6.10 so we are correct!
2G + 5M = £6.10 [note there really should NOT be £ signs in the question]
Yes - we need the same number of Gs or Ms so
1G + 2M = £2.80 (x2) 2G + 4M = £5.60
2G + 5M = £6.10 (x1) 2G + 5M = £6.10
so M = £0.50 or 50p
back in our first equation,
1G + 1 = £2.80
so G = £1.80 now check in the other equation: 3.60 + 2.50 does give 6.10 so we are correct!
I think the main thing is to show them that they need to get one of the 'unknowns' the same.... ie... 2 lots of 2G..........then it is just taking the smaller amount from the larger amount.
try it with simple sums
ie 1A + 3C = 11
2A + 4C = 16
multiply the first equation by 2 so that you have the same number of A's in both equations.
2A +6C = 22
minus the second one
2A +6C = 22
- 2A + 4C = 16
0 + 2C = 6
giving 2C = 6 therefore C = 3
sorry...... hope you can read this...haven't got the hang of getting them all under each other...
try it with simple sums
ie 1A + 3C = 11
2A + 4C = 16
multiply the first equation by 2 so that you have the same number of A's in both equations.
2A +6C = 22
minus the second one
2A +6C = 22
- 2A + 4C = 16
0 + 2C = 6
giving 2C = 6 therefore C = 3
sorry...... hope you can read this...haven't got the hang of getting them all under each other...
Yes, I can read it and it makes perfect sense...once someone has shown you how to do it. This was always my problem with maths...understanding it once it has been explained is one thing, working it out for yourself is quite another! Thanks very much for your help.
Guest 55-this question is from an independent school 11+ past paper. How they expect a 10/11 year old to be able to work it out I don't know. It's certainly not something that's been covered in the curriculum
Guest 55-this question is from an independent school 11+ past paper. How they expect a 10/11 year old to be able to work it out I don't know. It's certainly not something that's been covered in the curriculum
OrGuest55 wrote:1G + 2M = £2.80
2G + 5M = £6.10 [note there really should NOT be £ signs in the question]
Yes - we need the same number of Gs or Ms so
1G + 2M = £2.80 (x2) 2G + 4M = £5.60
2G + 5M = £6.10 (x1) 2G + 5M = £6.10
2G = 5.60 - 4M
2G = 6.10 - 5M
Therefore
5.60 - 4M = 6.10 - 5M
5M - 4M = 6.10 - 5.60
M = 0.50
Might seem convoluted, but may help in theory behind solving equations, and why you can subtract one equation from the other.