Submitted by Dharma

Questions
1) Nanyang 2010 P6 Prelim paper 1 Qn 21
The cost of 3 mangoes is the same as the cost of 5 grapefruits.
The cost of 3 mangoes is also the same as the cost of 10 pears.
Find the ratio of the cost of a mango to the cost of a grapefruit to the cost of a pear.
(ans : 10 : 6 : 3)

2) Nanyang 2010 P6 Prelim paper 1 Qn 30
The figure below is formed by stacking 4 pieces of square paper one on top of another. The papers have different prints and sizes (of sides 3cm, 4cm, 5cm and 6cm).
The 6-cm piece is placed at the bottom of the stack, followed by the 5-cm piece, then the 4-cm piece and the 3-cm piece is placed right on top.
Find the sum of the area A and B.
(ans : 8 cm2)

Suggested Answers

Nanyang 2010 P6 Prelim paper 1 Qn 21
3M = 5G
1M = 5/3 G
1M : 1G = 5 : 3 = 10 : 6

3M = 10P
1M = 10/3 P
1M : 1P = 10 : 3

1M : 1G : 1P = 10 : 6 : 3

Nanyang 2010 P6 Prelim paper 1 Qn 30
Area of large square – Area of yellow square = 6^2 – 3^2 = 36 – 9 = 27
Yellow square => 3 x 3
Orange square => 4 x 4
White square => 5 x 5
Blue square => 6 x 6

Length of A = Width of A = 6 – 4 = 2
Area of A = 2 X 2 = 4
Area of A = Area of B [Symmetry]
Area of A + Area of B = 4cm2 x 2 = 8cm2