Q&A - P3 Math

[Charnic]

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.

[smartmummy]

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.

A *** ```````
B *****``````
C *******````

In A length of * s is equal to length of `es in C.So Tin A contains 3 litres.Now we know Total length is 10 litres.So B is 10-5=5 Litres.C contains 10-3 is 7 litres.So 3+5+7=15 litres required to paint a complete wall.
Sorry I couldn't draw model and mark the length.Hope You understand.

[Charnic]

Sorry, I still could not see why Tin A contains 3 litres. Pls advise. Thanks

[smartmummy]

Hi CNS!

lenght of * =how many litres in the respective Tin
length of ` =how many litres sort for to paint the complete wall
X+7=Y+3, I think, obiviously X=3, Y=7.
If you draw the model manually u can see.

If we do by algebra method there are many possible answers,but for primary1/2 they don’t have algebra method.So just guess.

[corneyAmber]

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\">

[smartmummy]

Hi cns!


sorry for my answer.very tricky question!

[corneyAmber]

concern_parent:

Hi cns!


sorry for my answer.very tricky question!

yes I agree this question is indeed tricky.

[jedamum]

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

[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 why is 7-u+3-u --->5?
I do not quite understand this step.

[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.