Q&A - PSLE Math

[Dharma]

youngmum,


For your 2nd Qn,

1 unit used to represent the no. of red marbles transfered from Container A to Container B and 1 part used to represent the transfer of no. of blue marbles from Container A to Container B

If u are not comfortable w/ units and parts, u can use X and Y.

The 25% (Red) is the end result for Container A. Given in Qn. So, blue must be 75% for Container A.

[Dharma]

youngmum,


If distance is fixed, as given in Qn

The ratio of time is inversely proportional to the ratio of speed

Speed = 4:3
Time = 3:4

Distance = Speed x Time

D (fixed) = Speed (Increase) x Time (decrease) …and vice versa

[youngmum]

Thanks Dharma, i am still trying to figure it out. Really thanks so much. Sometimes i really wonder how can children 12 year old brain think so much.

[Dharma]

hi youngmum,


Qn 1 is not so easy a an average 12 yr old. Non-routine type qn …looks more like a maths olympiad type.

Forgot your Qn 4 earlier.

I used units and parts to represent proportion of apples and oranges b4 and after Mr Tan’s transactions respectively.

U can use anything else u like to represent the proportions…but need to understand that the proportions are not the same.

[Drdj]

Hi there,


I have a question from Red Swastika Prelim 2008 Paper.
The answer seems to give the area of the grille (784 cm2), but length of iron needed to make the grille should be the circumference, and length. Am I correct?


http://www.postimage.org/

[Drdj]

Drdj:

Hi there,


I have a question from Red Swastika Prelim 2008 Paper.
The answer seems to give the area of the grille (784 cm2), but length of iron needed to make the grille should be the circumference, and length. Am I correct?


http://www.postimage.org/

http://www.postimage.org/image.php?v=Pq1KGN99

[tianzhu]

Drdj:

Drdj:

Hi there,

I have a question from Red Swastika Prelim 2008 Paper.
The answer seems to give the area of the grille (784 cm2), but length of iron needed to make the grille should be the circumference, and length. Am I correct?

Hi
I think what you wanted is just to check the answer.It is 344cm.

[enoawng]

James Ang:

enoawng:

Can any help?


There were 186 adults in an auditorium. When 7/12 of the men and 4/9 of the women left the auditorium, the total number of adults who remained became 90. How many men were there in the auditorium at first?

let me try;

12/12 - 7/12 = 5/12 of men left behind
9/9 - 4/9 = 5/9 of women left behind

5/12 of men and 5/9 of women = 90
1/12 of men and 1/9 of women = 18
9/12 of men and 9/9 of men = 18x9 = 162
3/12 of men = 186 -162 = 24
12/12 of men = 24 x 4 = 96 men.

There are 96 men in the auditorium at first.

Thanks. However I think one step is missing for clarity, right?
9/12 of men and 9/9 of WOmen = 18x9 = 162 .........(1)
12/12 of men + 9/9 of WOmen = 186 .....................(2)
Subtracting (2) from (1)
3/12 of men = 186-162=24

Cheer

[Dharma]

http://www.postimage.org/

[small]

Drdj:

Drdj:

Hi there,


I have a question from Red Swastika Prelim 2008 Paper.
The answer seems to give the area of the grille (784 cm2), but length of iron needed to make the grille should be the circumference, and length. Am I correct?

HI Drdj,

agrred with Tianzhu, I think the answer should be 344 cm

28 x 4 = 112 ( the four sides)
28 x 2 = 56 ( the inner two bars)
2 x 22 / 7 x 7 x 4 = 176 ( the 4 circles )

112+ 56 + 176 = 344 cm