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P5 Simultaneous Equations & External Changed
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TOPIC: P5 Simultaneous Equations & External Changed
#4706
P5 Simultaneous Equations & External Changed 1 Year, 5 Months ago Karma: 1
There are 136 pupils in P5. 5/8 of the boys and 3/4 of the girls wear specs. There are 93 pupils who wear specs. How many boys are there in p5?
Cecilia Soh
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Last Edit: 2010/09/09 14:44 By Chris.
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#4711
Re:P5 Simultaneous Equations 1 Year, 5 Months ago Karma: 138
There are 136 pupils in P5. 5/8 of the boys and 3/4 of the girls wear specs. There are 93 pupils who wear specs. How many boys are there in p5?

For this question you can use Simultaneous Equations

First equation
5/8B + 3/4G --> 93
5/2B + 3G --> 93x4 = 372

Second equation
B + G --> 136
3B + 3G --> 136x3 = 408

Subtract First - Second
3B + 3G --> 136x3 = 408
5/2B + 3G --> 93x4 = 372
-------------------------
1/2B --> 36
Boys --> 72
Chris Rogers
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Last Edit: 2010/09/09 11:31 By Chris.
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#4717
Re:P5 Simultaneous Equations 1 Year, 5 Months ago Karma: 1
Thanks.... is there any "onsponge" method for this question?
Cecilia Soh
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#4719
Re:P5 Simultaneous Equations 1 Year, 5 Months ago Karma: 32
That is about the standard way to handle simultaneous equation.

Another possible presentation/working is shown below

spec 5B + 3G = 93
total 8B + 4G = 136

3xtotal 24B + 12G = 408
4xspe 20B + 12G .= 372
subtrt ..4B...............= ...36

B = 36/4 = 9
8B = 8 x 9 = 72
Reynold Tan
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#4720
Re:P5 Simultaneous Equations 1 Year, 5 Months ago Karma: 138
Yep. Simultaneous Equations

Some will learn this with Models, however, IMO, it is more difficult. If you understand it with Simultaneous,stick to it -- it's more efficient,
Chris Rogers
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#4725
Re:P5 Simultaneous Equations 1 Year, 4 Months ago Karma: 1
thanks.....
Cecilia Soh
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#4727
P5 External Changed (AKA Total Change) 1 Year, 4 Months ago Karma: 1
V gets 25% more pocket money than D. After she spent $50 and D spent $16, the ratio of the money she had left to the money D had left became 3:4. What was the pocket money that V had at first?
Cecilia Soh
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Last Edit: 2010/09/09 14:43 By Chris.
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#4729
Re:P5 External Changed (AKA Total Change) 1 Year, 4 Months ago Karma: 138
V gets 25% more pocket money than D. After she spent $50 and D spent $16, the ratio of the money she had left to the money D had left became 3:4. What was the pocket money that V had at first?

For this question we would follow the External Changed AKA Total Change approach.
Chris Rogers
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Last Edit: 2010/09/09 14:43 By Chris.
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