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Friday, November 17 2017 @ 08:55 PM CST
 Forum Index >  Test Paper Related >  Primary 5 Matters
 Area and Perimeter
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By: JessicaTan (offline)  Saturday, July 28 2012 @ 11:46 PM CDT (Read 1345 times)  
JessicaTan

Please help.

attachment with excel file 2003.[file]



Thanks
Jessica

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By: echeewh (offline)  Sunday, July 29 2012 @ 04:48 PM CDT  
echeewh

Hey Jessica,

Following pls find my worked solution (with reference to your attached question & figure ):

(a)

Given that 1/5 of triangle is shaded (ST), then 4/5 of triangle is Unshaded (UT). Likewise, if 2/7 of rectangle is shaded (SR), then 5/7 of rectangle is unshaded (UR).

We can express these as ratios (as shown):

** - buffer space for alignment purpose


UT : ST/SR : UR
4 * : ** 1
******* 2 ** : 5

Using <Repeated Identity> concept, we need to multiply 1st ratio 2x, as area of ST = area of SR. So we have ...

8 * : ** 2 ** : 5

Whole figure = 8u + 2u + 5u = 15u
Fraction of Whole figure shaded = 2/15

(b)

Given area of the shaded part is 28 cm2, we have ..

2u --> 28
1u --> 14
Total area of figure = 15u --> 15 x 14 = 210 cm2

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

Trust the above helps.

Do let me know again if this does not match your Answerkey or if there's any clarification.

Cheers,
Edward

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By: JessicaTan (offline)  Monday, July 30 2012 @ 03:56 AM CDT  
JessicaTan

Thanks Edward. Your answerkey is correct.

Appreciated your full working solution.

Rdgs
Jessica

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