Q&A - PSLE Math

[chl72]

Michael bought some apples and gave half of them to Jackson.

Jackson bought some pears and gave half of them to Michael.
Micheael threw away 25 pears that were rotten while Jackson bought for himself another 20 apples.
After that, the number of pears to apples Michael had were in the ratio of 1:4 and the number of pears to apples Jackson had were in the ratio of 1:2.
How many pears did Jackson buy?


Hi TianZhu,
Paisay to trouble you, what's the answer for this Q ah?
TIA

[tianzhu]

Hi kavisuresh


NY SA2 P6 Q3, 4 and 6 2010.
Please refer to Observer's solutions.

http://2.bp.blogspot.com/_EG8oMs7TIYA/TKh3WDOTKUI/AAAAAAAAAWQ/557Zb-x6l7c/s1600/MathsP610SA2FractionNYP2A03.jpg

http://2.bp.blogspot.com/_EG8oMs7TIYA/TKh3oc1SYlI/AAAAAAAAAWU/-f9Y8ar47TM/s1600/MathsP610SA2VolumeNYP2A04.jpg

http://psle2010a.blogspot.com/2010/10/whole-number-p6-2010-sa2-ny-p2-q6.html

Wishing you the very best for PSLE 2011.

Best wishes

[tianzhu]

chl72:

Hi TianZhu,
Paisay to trouble you, what's the answer for this Q ah?
TIA

Hi

The answer is 80.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=80

Best wishes

[WWong]

Hi,


I would like to seek some help, with thanks, on the below question.

1/3 of circle A is shaded and 3/7 of circle B is shaded. The ratio of the total area of circles A & B to the area of circle C is 5 : 8. What fraction of circle C is not shaded ?

http://i54.tinypic.com/flgewn.jpg\">

Thank you!

[tianzhu]

Hi WWong


Hi

You may start with assigning units to both shaded and unshaded regions of circle A , B and C until all conditions are met.

1/3 of circle A is shaded
Circle A ------- 1(shaded) : 2 (unshaded)

3/7 of circle B is shaded.
Circle B ------- 3(shaded) : 4(unshaded)

The ratio of the total area of circles A & B to the area of circle C is 5 : 8.

Total area of (A+B) :C --------5:8

Total area of (A+B) ------- 10 (3+7)

5:8 -------10:16

Total area of C --------- 16 units

Unshaded area of Circle C ------ 16 - 4 -----12

Fraction of circle C not shaded -------12/16 --------3/4

Best wishes

[WWong]

WWong:

Hi,


I would like to seek some help, with thanks, on the below question.

1/3 of circle A is shaded and 3/7 of circle B is shaded. The ratio of the total area of circles A & B to the area of circle C is 5 : 8. What fraction of circle C is not shaded ?

http://i54.tinypic.com/flgewn.jpg\">

Thank you!

Sorry. Still couldn't figure that out. Appreciate very much on the solution. Thank you very much.

[MathIzzzFun]

WWong:

Hi,


I would like to seek some help, with thanks, on the below question.

1/3 of circle A is shaded and 3/7 of circle B is shaded. The ratio of the total area of circles A & B to the area of circle C is 5 : 8. What fraction of circle C is not shaded ?

http://i54.tinypic.com/flgewn.jpg\">

Thank you!

Hi

There is some information missing... as it is, there will be more than one possible answer...

Let A = 15 units, B=35 parts
A, shaded = 5 units
B, shaded = 15 parts

C = (15units + 35 parts) / 5 x 8 = 24 units + 56 parts
C, unshaded = (24 - 5) units + (56 - 15 parts) = 19 units + 41 parts

Fraction of C that is unshaded
= (19 units + 41 parts )/(24 units + 56 parts)

So, depending on the relationship between 1 unit and 1 part, there could be more than one possible answer. For example,

if 1 unit = 1 part, we have
Fraction of C that is unshaded
= (19 units + 41 units) / (24 units + 56 units)
= 60 /80 = 3/4

If 1 unit = 2 parts, we have
Fraction of C that is unshaded
= (38 parts + 41 parts) / (48 parts + 56 parts)
= 79/104

so on and so forth....

cheers.

[chl72]

tianzhu:

chl72:

Hi TianZhu,
Paisay to trouble you, what's the answer for this Q ah?
TIA

Hi

The answer is 80.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=80

Best wishes

Hi Tianzhu,

:thankyou:

Cheers!

[tianzhu]

WWong:

Sorry. Still couldn't figure that out. Appreciate very much on the solution. Thank you very much.

Hi

Please refer to earlier post for solution.

I’ve provided the solution instead of links.

Best wishes

[tianzhu]

chl72:

Hi Tianzhu,

:thankyou:

Cheers!

Hi

You’re welcome.

Best wishes