Q&A - P3 Math

[dazzlego]

AgonyMum:

Please help to solve.Thanks very much!


1. A, B and C baked a totl of 119 cookies. A sold 5/11 of her share while B ate 15 cookies from her share. The number of cookies C ate was 3/5 the number of cookies A sold.If each of them has the same number of cookies left, how many cookies did C bake?

2. Pail X, Y and Z contained 6800ml of water altogether. 1/6 of the water in Pail Z and 500ml of water in Pail Y were poured out. THe volume of water poured out from Pail X was 5 times the volume of water poured out from Pail Z. Given that the 3 pails had the same volume of water left, find the volume of water in Pail Y at first.

Help u to do question 1
Then u can solve question 2 using the same concept

Assume A baked 11 units of cookies. He sold 5 units so in the end, he is left with 6 units.
B and C will have 6 units each in the end too.
Since C ate 3/5 of A (3 units), at first C baked 6+3 = 9 units.
At first, B = 6 units + 15

Total no. of cookies at first = 11u + 9u + (6u + 15) = 26u + 15
26u -> 119 - 15 = 104
1u -> 104 ÷ 26 = 4
C -> 9u -> 9 × 4 = 36

Cheers :celebrate:
Good luck for question 2!!
Answer should be 2 Litres :salute:

[Kiatkhim]

Anyone can help to interpret a problem sum in my DS SA2 Maths? I find the question quite confusing:-


Mr Yeong had to paint the chairs in the hall red or blue. After he had painted 1567 chairs, Mr Yeong still had another 865 chairs to paint. Given that he painted 769 chairs red, how may chairs were painted blue?

Thanks in advance!

[CayennePepper]

I try...

1567+865=2432 (total no. of chairs)
2432-769 red chairs=1663 blue chairs

That's my guess at how most kids will answer this.


BUT i find the phrasing open to interpretation.

-- After he had painted 1567 chairs, Mr Yeong still had another 865 chairs to paint. Given that he painted 769 chairs red, how may chairs were painted blue?

Seems like the 865 chairs is a red herring that should be ignored, since Mr Yeong had actually painted only 1567 chairs. So out of that, 1567-769=798 were painted blue.

What was the given answer?

[AgonyMum]

Thanks dazzlego for your help

Could you help to solve question 2 as well? I still could not solve it
BTW, can models be used to solve these 2 questions? Will it be an effective method?
Thanks in advance!

[sokk]

AgonyMum:

Please help to solve.Thanks very much!


1. A, B and C baked a totl of 119 cookies. A sold 5/11 of her share while B ate 15 cookies from her share. The number of cookies C ate was 3/5 the number of cookies A sold.If each of them has the same number of cookies left, how many cookies did C bake?

2. Pail X, Y and Z contained 6800ml of water altogether. 1/6 of the water in Pail Z and 500ml of water in Pail Y were poured out. THe volume of water poured out from Pail X was 5 times the volume of water poured out from Pail Z. Given that the 3 pails had the same volume of water left, find the volume of water in Pail Y at first.

Hi AgonyMum,
Hope this help, by using models for question 2.
Start by drawing the number of units for Pail Z . Since 1/6 (1 unit) of d water was poured out, that means 5/6 (5 units) of the water was left.
Since all 3 pails would hv d same volume of water left, u can proceed to draw 5 units each for Pail Y n Pail X.
Since we do not know d value of 1 unit, I wrote +500ml for Pail Y together with d 5 units already drawn.
Draw 5 more units for Pail X since d amt of water poured out from Pail X is 5 times that of Pail Z.



http://i46.tinypic.com/11igxf7.jpg\">

[dazzlego]

AgonyMum:

Thanks dazzlego for your help

Could you help to solve question 2 as well? I still could not solve it
BTW, can models be used to solve these 2 questions? Will it be an effective method?
Thanks in advance!

Hi AgonyMum,
Yes, you may draw the model. However, you still need to analyse the question in order to draw it.
Here is the model for question 1
http://i49.tinypic.com/30m8pcm.jpg\">

And for question 2, sokk has already helped you to draw the model and solve it

sokk:

Hi AgonyMum,
Hope this help, by using models for question 2.
Start by drawing the number of units for Pail Z . Since 1/6 (1 unit) of d water was poured out, that means 5/6 (5 units) of the water was left.
Since all 3 pails would hv d same volume of water left, u can proceed to draw 5 units each for Pail Y n Pail X.
Since we do not know d value of 1 unit, I wrote +500ml for Pail Y together with d 5 units already drawn.
Draw 5 more units for Pail X since d amt of water poured out from Pail X is 5 times that of Pail Z.

http://i46.tinypic.com/11igxf7.jpg\">

[dazzlego]

CayennePepper:

I try...

1567+865=2432 (total no. of chairs)
2432-769 red chairs=1663 blue chairs

That's my guess at how most kids will answer this.


BUT i find the phrasing open to interpretation.

-- After he had painted 1567 chairs, Mr Yeong still had another 865 chairs to paint. Given that he painted 769 chairs red, how may chairs were painted blue?

Seems like the 865 chairs is a red herring that should be ignored, since Mr Yeong had actually painted only 1567 chairs. So out of that, 1567-769=798 were painted blue.

What was the given answer?

What is your answer if u are the student, CayennePepper?
1663 or 798 :evil:

[AgonyMum]

Yeah, yeah! Thanks so much, sokk and dazzlego

I can understand both questions and their solutions now !
Really appreciate your help. THANKS!

[Riolu]

dazzlego:

CayennePepper:

I try...

1567+865=2432 (total no. of chairs)
2432-769 red chairs=1663 blue chairs

That's my guess at how most kids will answer this.


BUT i find the phrasing open to interpretation.

-- After he had painted 1567 chairs, Mr Yeong still had another 865 chairs to paint. Given that he painted 769 chairs red, how may chairs were painted blue?

Seems like the 865 chairs is a red herring that should be ignored, since Mr Yeong had actually painted only 1567 chairs. So out of that, 1567-769=798 were painted blue.

What was the given answer?

What is your answer if u are the student, CayennePepper?
1663 or 798 :evil:

Hmm... ... interesting

If this is a GEP type qn, answer can be 798 because \"Mr Yeong had actually painted only 1567 chairs\" and should ignore the \"865 chairs\" as yet to be painted. If this is a usual school exam question, answer may be 1663 as i believe is answer by most.

Well, open to interpretation lah! so what is the answer?

[CayennePepper]

dazzlego:

CayennePepper:

I try...

1567+865=2432 (total no. of chairs)
2432-769 red chairs=1663 blue chairs

That's my guess at how most kids will answer this.


BUT i find the phrasing open to interpretation.

-- After he had painted 1567 chairs, Mr Yeong still had another 865 chairs to paint. Given that he painted 769 chairs red, how may chairs were painted blue?

Seems like the 865 chairs is a red herring that should be ignored, since Mr Yeong had actually painted only 1567 chairs. So out of that, 1567-769=798 were painted blue.

What was the given answer?

What is your answer if u are the student, CayennePepper?
1663 or 798 :evil:

I pick... 798 lah
:nailbite: