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 Forum Index >  Test Paper Related >  Primary 6 Matters
 P6 Maths! 2012 Prelims Red Swastika Paper 2 Q14 & Q15
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By: geniuskids (offline)  Sunday, September 08 2013 @ 08:41 AM CDT (Read 827 times)  
geniuskids

Hi there, pls refer to upload. Pls help. Tx

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By: echeewh (offline)  Sunday, September 08 2013 @ 08:22 PM CDT  
echeewh

Hello <geniuskids>,

// 9/9/13, 12:10
Corrected and re-edited Q15
//


Appreciate that <Answerkey> be provided for verification purpose.

Following are my worked solutions.

Q14

<Fig1>
Vol of water in container:
Area × Height = 120 × 6 = 720 cm3

Vol of Container + Vol of *White spaces:
120 × 15 = 1800 cm3

*Note: White spaces refers to the 3 void/empty spaces/areas outside the container at the top (see Fig 1) or bottom (see Fig 2)

<Fig 2>
Vol of water + Vol of *White spaces
= 120 × 7 = 840 cm3

Vol of *White spaces = 840 - 720 = 120 cm3

Hence, Capacity of Container
= 1800 - 120
= 1680 cm3
= 1.68 litres

============

Q15

<Fig 1>
Unshaded Area
= Area of Triangle × 2
= [(80 × 40) / 2] × 2
= 3200 cm2

<Fig 2>
Construct a horizontal line and vertical line similar to Fig 1. And there are 4 identical small Squares and Quadrants.

Unshaded Area of 1 Small Square
= Area of small Square - Shaded Segment (half-leaf) of Quadrant
= Area of small Square - Quadrant + Area of Triangle (enclosed by the Quadrant)
=(40 × 40) - ([3.14 × 40 × 40] / 4) + [(40 × 40) / 2]
= 1600 - 1256 + 800
= 1144 cm2

Unshaded Area of 4 Small Squares
= 4 × 1144 = 4576 cm2

Difference in Unshaded Areas
= 4576 - 3200
= 1376 cm2

========

Trust this helps.

Do let me know again if this is different from your <Answerkey> or if there are further clarifications.

Cheers,
Edward

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By: geniuskids (offline)  Sunday, September 08 2013 @ 09:32 PM CDT  
geniuskids

Q14 Your answer same as answer key
Q15 Answer key is 1376 cm2.

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By: echeewh (offline)  Sunday, September 08 2013 @ 11:10 PM CDT  
echeewh

Thank you <geniuskids> for the <Answerkey>.

Q15 was corrected and re-edited (with a missing step) on 9/9/13, 12 10.

Cheers,
Edward

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By: geniuskids (offline)  Monday, September 09 2013 @ 03:16 AM CDT  
geniuskids

Hi,

I understand Q15 now but need to clarify on Q14.

Don't get this part : Vol of container + Vol of white spaces: 120 x 15 = 1800cm3 ???

Pls explain this question again!

Thank you

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By: echeewh (offline)  Monday, September 09 2013 @ 06:21 PM CDT  
echeewh

Hey <geniuskids>,

The Vol of White spaces refers to the 3 void/empty spaces/areas outside the container at the top (see Fig 1) or bottom (see Fig 2).

And this Volume of (120 × 15 = 1800 cm3) includes both the Volumes of the Container and these 3 void/empty areas as seen in both the Figures.

========

Trust this clarifies.

Thank you and best regards,
Edward

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