Q&A - PSLE Math

[kiasiparent]

Awesome question. Keep up the good work.

[Jusmum]

:?: Could you help with this P6 holiday question...


It takes 5 hours for June to complete spring cleaning her house. If Sam helps her, they will take 3 hours to complete. Is Sam were to do alone, how long will she take?

Thanks!

[CoffeeCat]

Jusmum:

:?: Could you help with this P6 holiday question...


It takes 5 hours for June to complete spring cleaning her house. If Sam helps her, they will take 3 hours to complete. Is Sam were to do alone, how long will she take?

Thanks!

Since its a rate question one should start by finding the rate
June
5 hrs --> clean the house completely
1hr --> clean 1/5 of hourse

Sam + June
3 hrs --> clean house completely
1hr --> clean 1/3 house

therefore
Sam
1hr --> clean (1/3 - 1/5) = 2/15 of house
time taken = 15/2 = 7.5 hrs

[Dharma]

Jusmum:

:?: Could you help with this P6 holiday question...


It takes 5 hours for June to complete spring cleaning her house. If Sam helps her, they will take 3 hours to complete. Is Sam were to do alone, how long will she take?

Thanks!

June takes 5 hrs to clean 1 house
June takes 1 hr to clean 1/5 house

June & Sam take 3 hrs to clean 1 house
June & Sam take 1 hr to clean 1/3 house

In 1 hr, Sam can clean (1/3-1/5 = 2/15) of the house.
Sam takes 7.5 hrs to clean the house on her own.

[Jusmum]

Oh, my…thanks so much Coffeecat and Dharma…that was fast…glad I can help my girl now…


But the school has not taught this topic yet…thot it was average question…silly me…

thanks again!

[CoffeeCat]

Jusmum:

Oh, my...thanks so much Coffeecat and Dharma.....that was fast...glad I can help my girl now...


But the school has not taught this topic yet...thot it was average question...silly me...

thanks again!

Hmm i thought rate was out of the syllabus anyway?

[P5G]

Please help.


Paper 2 Q18
http://www.orlesson.org/orp/09Ma/2009-Math-CA1-NanHua.pdf

Please advise how I could find the sum of the numbers in the 10th row without having to list out all the numbers in the 7th, 8th and 9th rows?

TIA.

[Dharma]

P5G:

Please help.


Paper 2 Q18
http://www.orlesson.org/orp/09Ma/2009-Math-CA1-NanHua.pdf

Please advise how I could find the sum of the numbers in the 10th row without having to list out all the numbers in the 7th, 8th and 9th rows?

TIA.

http://www.postimage.org/image.php?v=gx6euWr

[James Ang]

P6 now learning Percentage topic, a question to share with students here;


Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles. How many red marbles and how many blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in Container B are red.

[Tang]

James Ang:

P6 now learning Percentage topic, a question to share with students here;


Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles. How many red marbles and how many blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in Container B are red.

A -- 25 : 75 = 1 : 3

B -- 75 : 25 = 3 : 1

A + 3 B --> 250 + 600 = 850

3 A + B --> 200 + 150 = 350

4 A + 4 B --> 850 + 350 = 1200
1 A + 1 B --> 1200 / 4 = 300

2 B --> 850 - 300 = 550
B --> 550 / 2 = 275

2 A --> 350 - 300 = 50
A --> 50 / 2 = 25

250 - 25 = 225 red

200 - 25 x 3 = 125 blue (or 275 - 150 = 125 blue)

So move 225 red marbles and 125 blue marbles from Container A to Container B.