Q&A - PSLE Math

[MathIzzzFun]

Belle2011:

Dear all,

I need some help on this problem.

At a fitness carnival, 1600 people participated in a Mass Dance and Taiji. 30% of the 1300 Mass Dance participants were adults. 40% of the Taiji participants were children. During the break, some Mass Dance participants went on to participate in Taiji, while some Taiji participants went on to participate in the Mass Dance. After the change, 25% of the Mass Dance participants and 75% of the Taiji participants were adults. How many Mass Dance participants were there after the change?

model answer: 1260

Thank-you.

Cheers,
Belle.

hi

http://i53.tinypic.com/1zbw0f6.jpg\">

cheers.

[corneyAmber]

ivanhoo99:

ksi:

[quote=\"bobsg01\"]Pri. 6 Vol. of Liquids question.


Thanks for helping. :scratchhead:

http://i54.tinypic.com/15ez0pg.jpg\">

Assuming p6 knows cube root?
Then it is easy, cube root of 216 = 6
Hence the l x b x h = 6 x 6 x 6 for container A.

If container B has the same height and breadth as container A, then to fill half of the tank = 15.4 x 6 x 3 = 277.2 cubic cm

Is the Ans suppose to be 61.2? Because they ask for how much MORE water is needed to fill half of it.[/quote]
Sorry I misread. yes 216 cubic cm of water is already inside the container B, so to make it half-filled, must take 277.2-216 = 61.2 cubic cm.

[chrisu]

Hi need help for this question;


The figure below, not drawn to scale, shows 2 semi-circles and a right-angled triangle overlapping one another. The diameter of the smaller semi-circle is half of the bigger semi-circle. Find the area of the shaded part given that the diameter of the bigger semi-circle is 40cm.
Give your answer correct to 2 decimal places.

http://img.photobucket.com/albums/v160/guppiesonli/Misc/Q18.jpg\">

[PiggyLalala]

chrisu:

Hi need help for this question;


The figure below, not drawn to scale, shows 2 semi-circles and a right-angled triangle overlapping one another. The diameter of the smaller semi-circle is half of the bigger semi-circle. Find the area of the shaded part given that the diameter of the bigger semi-circle is 40cm.
Give your answer correct to 2 decimal places.

http://img.photobucket.com/albums/v160/guppiesonli/Misc/Q18.jpg\">

area of shaded area = area of big semicircle + area of small semicircle - area of triangle
= 0.5 X3.142 X 20 X 20 + 0.5 X3.142 X 10 X 10 - 1/2 X 20 X 40 ( use the calculator pie)
=385.40 cm square

[chrisu]

Thank you, didn't realise it's just so straight forward. Makes my day.

PiggyLalala:

chrisu:

Hi need help for this question;

The figure below, not drawn to scale, shows 2 semi-circles and a right-angled triangle overlapping one another. The diameter of the smaller semi-circle is half of the bigger semi-circle. Find the area of the shaded part given that the diameter of the bigger semi-circle is 40cm.
Give your answer correct to 2 decimal places.

http://img.photobucket.com/albums/v160/guppiesonli/Misc/Q18.jpg\">

area of shaded area = area of big semicircle + area of small semicircle - area of triangle
= 0.5 X3.142 X 20 X 20 + 0.5 X3.142 X 10 X 10 - 1/2 X 20 X 40 ( use the calculator pie)
=385.40 cm square

[tianzhu]

ivanhoo99:

May i know which book you had taken from? Im also troubled by the question as i dunno how to do. Thx!!!

Hi

This question is from Singapore Chinese Girls' School (Primary) P6 Prelim 2010 Paper 2 Q17.

Please go to page 22 of this link.

http://www.orlesson.org/orp/10Ma/2010-P6-Math-SA2-SCGS.pdf

Best wishes

[Belle2011]

Dear tianzhu and MathIzzzFun,

Thank-you for sharing your solutions.

Cheers,
Belle.

[bobsg01]

10q to ksi and ivanhoo99 for the answers.


:celebrate: :hi5:

[bobsg01]

P6 Pie Charts question. :faint:


Appreciate the kind help.

http://i51.tinypic.com/2isxyzd.jpg\">

[Kloggy]

stary:

Kloggy:

Hi,


Need help on following 2 qns from Maha Bodhi, 2010, Prelim.

2) Paper 2, qn 13.
Diagram shows two containers X and Y.
Container X is being filled by tap B
Container Y is being filled by tap A.
Container X has base of 25 cm by length (which is unknown)
Container Y has base of 50 cm by 45 cm

Here is the qn :
In every minute, three times as much water flows out of Tap A as Tap B into two empty containers, X and Y.
After 20 minutes, container X is 2/5 filled with water and the height of the water level in container X is the same as that of container Y.
(a) what is the length of the base of container X?
(b) How many litres of water can container X hold ?

I managed to find the answer to (a), which is 30 cm.
But how to do part (b) ? (Ans : 56.25)

Pls help !!!!!
Thanks.

Base area of Container Y -> 50 x 45 = 2250 cm2
Base area of Container X -> 2250/3 = 750 cm2
Length of Container X -> 750/25 = 30 cm(a)

Time to fill Container X -> 5/2 x 20 = 50 min
Height -> 3/2 x 50 = 75cm
Water to fill Container X -> 25x30x75 = 56250 cm3 = 56.25 litres(b)

Thanks a lot, but I don't understand why the height is 3/2 x 50. Can help to explain ?