Q&A - P3 Math

[PiggyLalala]

ksi:

Hi CNS and concerned_parent, the key in this question is that all 3 cans of paint must be used for the wall.


http://i53.tinypic.com/2418tch.jpg\">

Thank you for the solution.
But why is 7-u+3-u --->5?
I do not quite understand this step.

[MathIzzzFun]

CNS:

Pls help me on the P3 maths:

Tin A, Tin B and Tin C are required to paint a complete wall. If only Tin A is used, we are short of 7litres. If only Tin B is used, we are short of 5 litres. If only Tin C is used, we are short of 3 litres. How many litres of paint is required to paint a complete wall? TIA.

Hi

Another approach ..

http://www.flickr.com/photos/62167097@N02/5804257287/in/photostream

http://i56.tinypic.com/2n1gyuw.jpg\">

cheers.

[corneyAmber]

PiggyLalala:

ksi:

Hi CNS and concerned_parent, the key in this question is that all 3 cans of paint must be used for the wall.


http://i53.tinypic.com/2418tch.jpg\">

Thank you for the solution.
But why is 7-u+3-u --->5?
I do not quite understand this step.

From first model, we get tin C =7-u
From 3rd model, we get tin A = 3-u
From 2nd model we know that since tin B is used, the remaining 5 litres must come from tin C and tin A, hence
7-u +3-u -> 5

Okie dokie?

[corneyAmber]

PiggyLalala:

ksi:

Hi CNS and concerned_parent, the key in this question is that all 3 cans of paint must be used for the wall.


http://i53.tinypic.com/2418tch.jpg\">

Thank you for the solution.
But why is 7-u+3-u --->5?
I do not quite understand this step.

From first model, we get tin C =7-u
From 3rd model, we get tin A = 3-u
From 2nd model we know that since tin B is used, the remaining 5 litres must come from tin C and tin A, hence
7-u +3-u -> 5

Okie dokie?

[Thein]

jedamum:

P3 Math?! even with the solution, i am still seeing stars....:faint:

me too agree............

[PiggyLalala]

ksi:

PiggyLalala:

[quote=\"ksi\"]Hi CNS and concerned_parent, the key in this question is that all 3 cans of paint must be used for the wall.


http://i53.tinypic.com/2418tch.jpg\">

Thank you for the solution.
But why is 7-u+3-u --->5?
I do not quite understand this step.

From first model, we get tin C =7-u
From 3rd model, we get tin A = 3-u
From 2nd model we know that since tin B is used, the remaining 5 litres must come from tin C and tin A, hence
7-u +3-u -> 5

Okie dokie?[/quote] :thankyou: Now i understand the solution fully. :thankyou:

[PiggyLalala]

MathIzzzFun:

CNS:

Pls help me on the P3 maths:

Tin A, Tin B and Tin C are required to paint a complete wall. If only Tin A is used, we are short of 7litres. If only Tin B is used, we are short of 5 litres. If only Tin C is used, we are short of 3 litres. How many litres of paint is required to paint a complete wall? TIA.

Hi

Another approach ..

http://www.flickr.com/photos/62167097@N02/5804257287/in/photostream

http://i56.tinypic.com/2n1gyuw.jpg\">

cheers.

:thankyou: for the clear model drawn.

[Charnic]

Thein:

jedamum:

P3 Math?! even with the solution, i am still seeing stars....:faint:

me too agree............

I solve it via the alegbra method. Still comtemplating if I should expose my gal to these questions. Personally I thought they are too difficult for the P3s. Any P3 parents care to share if your child can attempt the question without any help ?

[MathIzzzFun]

PiggyLalala:

MathIzzzFun:

[quote=\"CNS\"]Pls help me on the P3 maths:

Tin A, Tin B and Tin C are required to paint a complete wall. If only Tin A is used, we are short of 7litres. If only Tin B is used, we are short of 5 litres. If only Tin C is used, we are short of 3 litres. How many litres of paint is required to paint a complete wall? TIA.

Hi

Another approach ..

http://www.flickr.com/photos/62167097@N02/5804257287/in/photostream

http://i56.tinypic.com/2n1gyuw.jpg\">

cheers.

:thankyou: for the clear model drawn.[/quote]you are welcome

cheers.

[PiggyLalala]

After understanding the solution posted by Ksi and MathIzzzFun, I think Ksi is right: the key in this question is that all 3 cans of paint must be used for the wall.


Perhaps the question can be rephrased to
To paint a complete wall, we need exactly one tin of Paint A, one tin of paint B and one tin of paint C. If only Paint A is used, we are short of 7litres. If only Paint B is used, we are short of 5 litres. If only Paint C is used, we are short of 3 litres. How many litres of paint is required to paint a complete wall? Would this be better?