Q&A - PSLE Math

[Dharma]

Brenda10:

Belle2011:

[quote=\"Brenda10\"]
Hi, this question was from NY 2010 CA1 P2 Q17.

3/5, 1/4

12/20 , 5/20

300 x 12/20 = 180, 180 x 5/20 = 45
300- 180 = 120, 180 - 45 = 135

2u = 120 + 45 + 300 - 135
2u = 330
1u = 165

Julian: 5u + 300
5 * 165 + 300 = 1125

Thank you

Similarly, can anybody offer some detailed explanation?
What does 300- 180 = 120, 180 - 45 = 135 mean?
How to get 2u = 120 + 45 + 300 = 135 ?

Thanks.

Oh there is a typing error, should be:

2u = 120 + 45 + 300 -135

Sorry as I just transferred dd's working and can't help in explanation. Hopefully someone else can help.[/quote]Sorry, just another way of presentation.

Julian gave 3/5 of his cards to Faizal
Julian : 100u – 60u = 40u
Faizal : (100u – 300) + 60u = 160u – 300

Faizal gave ¼ of his cards to Julian
Julian : 40u + (40u – 75) = 80u - 75
Faizal : (160u – 300) – (40u – 75) = 120u – 225

Difference = 120u – 225 – (80u – 75) = 300
40u = 300 + 150 = 450

No. of cards Julian had at first = 100u = 450/40 x 100 = 1125

[Belle2011]

Dharma:

Julian gave 3/5 of his cards to Faizal

Julian : 100u – 60u = 40u
Faizal : (100u – 300) + 60u = 160u – 300

Faizal gave ¼ of his cards to Julian
Julian : 40u + (40u – 75) = 80u - 75
Faizal : (160u – 300) – (40u – 75) = 120u – 225

Difference = 120u – 225 – (80u – 75) = 300
40u = 300 + 150 = 450

No. of cards Julian had at first = 100u = 450/40 x 100 = 1125

Hello Dharma,
You have \"assigned\" 100u to Julian and thus Faizal has 100u-300 etc
Thank-you for your explanation.
BTW, can you offer a similar explanation/working for the other question mentioned earlier, please?
Cheers,
Belle.

[Dharma]

Belle2011:

Dharma:

Julian gave 3/5 of his cards to Faizal

Julian : 100u – 60u = 40u
Faizal : (100u – 300) + 60u = 160u – 300

Faizal gave ¼ of his cards to Julian
Julian : 40u + (40u – 75) = 80u - 75
Faizal : (160u – 300) – (40u – 75) = 120u – 225

Difference = 120u – 225 – (80u – 75) = 300
40u = 300 + 150 = 450

No. of cards Julian had at first = 100u = 450/40 x 100 = 1125

Hello Dharma,
You have \"assigned\" 100u to Julian and thus Faizal has 100u-300 etc
Thank-you for your explanation.
BTW, can you offer a similar explanation/working for the other question mentioned earlier, please?
Cheers,
Belle.

Dolly gave 25% of her stickers to Jenny
Dolly : 100u – 25u = 75u
Jenny : (100u – 80) + 25u = 125u – 80

Jenny gave 60% of her stickers to Dolly
Dolly : 75u + (75u – 48 ) = 150u - 48
Jenny : (125u – 80) – (75u – 48 ) = 50u – 32

Difference = (150u – 48 ) – (50u – 32) = 100
100u – 16 = 100
100u = 116

No. of stickers Dolly had at first = 100u = 116

[Brenda10]

Dharma:

Dolly gave 25% of her stickers to Jenny

Dolly : 100u – 25u = 75u
Jenny : (100u – 80) + 25u = 125u – 80

Jenny gave 60% of her stickers to Dolly
Dolly : 75u + (75u – 48 ) = 150u - 48
Jenny : (125u – 80) – (75u – 48 ) = 50u – 32

Difference = (150u – 48 ) – (50u – 32) = 100
100u – 16 = 100
100u = 116

No. of stickers Dolly had at first = 100u = 116

Hi Dharma

Thank you for providing another method of doing as dd can also learn another way of solving problem.

[Belle2011]

Dharma:

Dolly gave 25% of her stickers to Jenny

Dolly : 100u – 25u = 75u
Jenny : (100u – 80) + 25u = 125u – 80

Jenny gave 60% of her stickers to Dolly
Dolly : 75u + (75u – 48 ) = 150u - 48
Jenny : (125u – 80) – (75u – 48 ) = 50u – 32

Difference = (150u – 48 ) – (50u – 32) = 100
100u – 16 = 100
100u = 116

No. of stickers Dolly had at first = 100u = 116

Dear Dharma,
Thanks very, very much for your help.
Cheers,
Belle

[tianzhu]

[quote]4u+ 60 + 12 = 100 + 8

4u + 72 = 108
4u = 108 - 72
4u = 36[/quote][quote]2u = 120 + 45 + 300 - 135
2u = 330
1u = 165[/quote]Hi Brenda10

I am curious to know how your dd got to these steps.Did she use Model Drawing or Units Method?

Best wishes

[Brenda10]

tianzhu:

[quote]4u+ 60 + 12 = 100 + 8

4u + 72 = 108
4u = 108 - 72
4u = 36

[quote]2u = 120 + 45 + 300 - 135
2u = 330
1u = 165[/quote]Hi Brenda10

I am curious to know how your dd got to these steps.Did she use Model Drawing or Units Method?

Best wishes[/quote]Hi Tianzhu

DD learn from one of the book that we got. This book has similar example to the question we encountered. Its come with model but by following the example she did not draw the model. Have PM for you.

Thank you

[Belle2011]

Brenda10:

Hi Tianzhu


DD learn from one of the book that we got. This book has similar example to the question we encountered. Its come with model but by following the example she did not draw the model. Have PM for you.

Thank you

Dear Brenda10,
Can you share the same of this book?
I cannot solve these problems at all. Maybe my IQ is just too low. I often cannot handle the last few (4 or 5 marks) questions.
Thank-you.
Cheers,
Belle.

[Brenda10]

Dear Belle


Don't under estimate yourself. Important thing is to practice as many as possible and look out/source a way/method that you find is comfortable and easier to understand and remember. Have PM for you.

Thank you

[Belle2011]

Another tricky question:

It takes 3 men 4 days to paint 3 houses. How long does it take 4 men to paint 9 houses?
Thank-you.