Q&A - P3 Math

[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?

[PiggyLalala]

After rephrased the question, I discussed the question with my P3 child again. I told him that to paint the wall, we need exactly a tin of Paint A, a tin of paint B and one tin of paint C, that is

A + B + C = Wall

Next, I guide him to tell me what information can we deduce from the statement 'If only Paint A is used, we are short of 7litres.'
He told me B + C = 7
Similarly from the next two statements, we know that A + C = 5
and A + B = 3.

Then I reminded him that we have managed to reduce the question to a similar question that he has done before in P1 and P2:
* + @ = 10
* +* - @ = 2.
What is * and @?

Back to the 'Paint question', my son then told me that
2A + 2B + 2C = 5 + 3 + 7 = 15
therefore A + B + C = 15/2 = 7.5

That is the wall needs 7.5 litres of paint.
This is an alternative approach from me and my son after understanding the question with the help of Ksi and MathIzzzFun. What about yours?

Maths is FUN because it can be done by a few approaches. :lol:

[PiggyLalala]

Another approach ..


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

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

cheers.[/quote]

Really like your approach to this question. Never thought that the question be done using model. Cool. From the first bar, we know that
B + C = 7. Then it is back to the usual P1 and P2 model.

B: XXXXXXXX<-----2litres--->
XXXXXXXXXXXXXXXXXXXX
Therefore 2 units = 7 -2 = 5
1 unit = 5/2 = 2.5
B: 2.5

Back to MathIzzzFun model: Therefore the wall: 5 + 2.5 = 7.5 litres.
I really like this approach.

[MathIzzzFun]

PiggyLalala:

PiggyLalala:

After rephrased the question, I discussed the question with my P3 child again. I told him that to paint the wall, we need exactly a tin of Paint A, a tin of paint B and one tin of paint C, that is
A + B + C = Wall

Next, I guide him to tell me what information can we deduce from the statement 'If only Paint A is used, we are short of 7litres.'
He told me B + C = 7
Similarly from the next two statements, we know that A + C = 5
and A + B = 3.

Then I reminded him that we have managed to reduce the question to a similar question that he has done before in P1 and P2:
* + @ = 10
* +* - @ = 2.
What is * and @?

Back to the 'Paint question', my son then told me that
2A + 2B + 2C = 5 + 3 + 7 = 15
therefore A + B + C = 15/2 = 7.5

That is the wall needs 7.5 litres of paint.
This is an alternative approach from me and my son after understanding the question with the help of Ksi and MathIzzzFun. What about yours?

Maths is FUN because it can be done by a few approaches. :lol:

Hi

Math is fun indeed. But many children will inevitably be intimidated by seemingly tough questions and find it boring zzz ... I hope to share different approaches to problem solving and hopefully this will make it from zzz to fun - which is why I use the moniker mathizzzfun

back to the same problem, after you reach
B+C = 7
A+C = 5
A+B = 3

we are back to the typical \"shapes\" type of question

cheers.