
By: geniuskids (offline) Tuesday, April 30 2013 @ 10:42 AM CDT (Read 1292 times)



geniuskids 
Hi there, pls help solve these Qs
Did not upload Q13, kindly refer to the test paper for diagram.
Q15 Yuna was packing some notebooks into green, yellow and white boxes. A green box was able to hold thrice as many notebooks as a yellow box and 2/5 as many notebooks as a white box. The ratio of the number of green boxes used to the number of yellow boxes used to the number of white boxes used was 5:8:2. If Yuna had a total of 912 notebooks to pack, how many notebooks did she pack into all the yellow boxes?
Many thanks for yr help!

Active Member
Registered: 11/12/11 Posts: 169





By: echeewh (offline) Wednesday, May 01 2013 @ 09:50 PM CDT



echeewh 
Hi there,
Following pls find my worked solutions:
Q13
For the purpose of all readers / viewers, will attach the diagram later.
//
Updated:
Question/Diagram attached on 13 June 2013.
//
Entire solution is based on method of proportions (ratio) and Area of Triangle.
AB : MB
4 : 1
So,
AM : MB
3 : 1
Given BL is twice PB and since these are the respective perpendicular heights for triangles LBM and PBM,
Area LBM = 2 × Area PBM {both triangles have common base, MB}
= 2 × 6 = 12 cm2
Area LMN = 2 × Area LBM {from given figure}
= 2 × 12 = 24 cm2
Since AM and MB are the respective perpendicular heights for triangles KMN and LMN,
Area KMN = 3 × Area LMN {both triangles have common base, MN}
= 3 × 24 = 72 cm2
Hence,
Area KMLN = Area KMN + Area LMN
= 72 + 24
= 96 cm2
=========
Q15
Boxes
G : Y : W
5 : 8 : 2
Notebooks:
G : Y
3 : 1  (1)
G : W
2 : 5  (2)
Using <Repeated Identity> method, multiply (1) 2x, (2) 3x.
G : Y
6 : 2
G : W
6 : 15
Hence,
Notebooks:
G : Y : W
6 : 2 : 15
Using <Number x Value> method, we have ...
(5p × 6u) + (8p × 2u) + (2p × 15u) = 912
30pu + 16pu + 30pu > 912
76pu > 912
1pu > 912 ÷ 76 = 12
Y = 16pu > 16 × 12 = 192
===========
Trust the above helps.
Do let me know again if there's further clarification.
Cheers,
Edward

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Registered: 04/21/11 Posts: 627





By: echeewh (offline) Thursday, June 13 2013 @ 08:09 AM CDT



echeewh 
Dear ALL,
FYI
Q13  Question/Diagram attached on 13 June 2013.
Thank you and best regards,
Edward

Active Member
Registered: 04/21/11 Posts: 627



