Q&A - PSLE Math

[tianzhu]

Vanilla Cake:

Hope that other members can come forward with pictorial diagram to help you understand better.

Hi Vanilla Cake

Hope this may help.

To all dads in KSP, enjoy the cookies and have a happy and memorable Father’s Day.

http://farm5.static.flickr.com/4019/4713599224_8f586290c0_b.jpg\">

Best wishes.

[abc_parent]

Hi gurus !

Can anyone tell me for this particular question, why the solution for line 3 is so? Where is the area of circle in the question?

The diagram can be found here:
-> http://psle2010a.blogspot.com/search/label/M%20Circle%20P6%20RGS

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1/2 x 3.14 x 4 x 4 = 25.12


33.5 – 25.12 = 8.38


3.14 x 8 x 8 = 200.96 (can someone explain this step?)


200.96 – 8.38 – 8.38 = 184.2 cm2 (can someone also explain this step?)

[Pen88n]

Let me try this:


1/2 x 3.14 x 4 x 4 = 25.12
(This is to get the area of semi-circle with diameter EF)

33.5 – 25.12 = 8.38
(This is to get area of unshaded odd shape minus semi-circle EF)

3.14 x 8 x 8 = 200.96 (can someone explain this step?)
200.96 – 8.38 – 8.38 = 184.2 cm2 (can someone also explain this step?)

(If you look carefully, you will notice the centre piece is also derived from 2 quarter circles of radius 8cm - like the shaded 2 quarter circles. The way to get the shaded area is then to get the area of 4 quarter circles - 1 whole circle - and deduct the unshaded odd shape twice from the 2 quarter circles.)

Hope this helps

[tianzhu]

Hi


I tried but couldn't get a nice drawing because I don't know how to draw a quadrant using PowerPoint.

For those who knows how to draw a quadrant, please teach me.

I believe you should be able to carry on with the rest of the steps.

Hope this helps.

http://farm5.static.flickr.com/4021/4714317368_f4ca67939b_b.jpg\">

Best wishes

[angela]

Hi,


anyone can advise?

Example:

John took 2 hour to travel from home to school and took 2 hour 30 minutes to travel from school to playground. What was the time taken that John taken to travel for the whole journey?

The answer is 4 hour 30 minutes but how to show working.

2 hour + 2 hour = 4 hours

4 hours 30 minutes. (correct?)

Thks

[abc_parent]

thanks to tianzhu and pen88n!

[abc_parent]

May I know how to solve the following , gurus?


Q12
-> In the figure, the shaded portion shows a 3m wide cemented walkway in a rectangular field of length 40cm and breadth 20m. Besides the walkway, rest of the rectangular field is covered with grass.
(a) Find the area of the walkway. (why is the answer 20m x 3m?)
(b) Find the area of the field that is covered with grass.

Q14
-> If Ahmad and Ben work together, they can complete a job in 12 days. If Ahmad and Ben worked together for 3 days, followed by Ben who worked alone for the next 5 days, they can finish 5/12 of the job. How many days will each of them need to complete the job if they were to work alone?

Q15 (comes with a hexagon of length 0.5km and label ABCDEF in clockwise manner)
–>Tommy and Wilson jog on a hexagon track (6 equal sides) at 8am. Tommy starts at point C while Wilson starts at point F. Both jog in the direction as shown by the arrows. (clockwise direction shown) Tommy’s speed is 1.5 times Wilson’s.
(a) At which point will they meet?
(b) If they meet at 8.20am, find Tommy’s speed?

[corneyAmber]

http://i724.photobucket.com/albums/ww246/ks2me/P6MathRGPSSA1200915b-1.jpg\">

[corneyAmber]

angela:

Hi,


anyone can advise?

Example:

John took 2 hour to travel from home to school and took 2 hour 30 minutes to travel from school to playground. What was the time taken that John taken to travel for the whole journey?

The answer is 4 hour 30 minutes but how to show working.

2 hour + 2 hour = 4 hours

4 hours 30 minutes. (correct?)

Thks

Is this a P6 question? Time can be expressed in fractions.
If one feels the need to show working, then 2+2 1/2 = 4 1/2 = 4 hrs 30 mins.

[corneyAmber]

Q12

-> In the figure, the shaded portion shows a 3m wide cemented walkway in a rectangular field of length 40cm and breadth 20m. Besides the walkway, rest of the rectangular field is covered with grass.
(a) Find the area of the walkway. (why is the answer 20m x 3m?)
(b) Find the area of the field that is covered with grass.

I cannot find the diagram on the net, can you furnish the diagram?