The figure, not drawn to scale, is made up of two identical squares, W and Y and a rectangle X. The ratio of the area W to the area of X to the area of Y is 1 : 2 : 1. The ratio of the unshaded part of W to the unshaded part of Y is 2 : 3 respectively. Given that half of the area of W is shaded and the total area of all the shaded parts is 24 cm
2, what is the area of the whole figure?
W |
X |
Y |
1x4 = 4 u |
2x4 = 8 u |
1x4 = 4 u |
Unshaded |
Shaded |
Unshaded |
Shaded |
Unshaded |
Shaded |
|
2 |
|
|
3 |
|
1x2 |
1x2 |
|
|
|
|
2 u |
2 u |
5 u |
3 u |
3 u |
1 u |
Since half of the area of W is shaded, the other half of the area of W is unshaded.
Unshaded part of W : Shaded part of W
1 : 1
The unshaded part of W is the repeated identity.
LCM of 1 and 2 = 2
Area of W is the combined repeated identity.
LCM of 1 and 4 = 4
W : X : Y
1 : 2 : 1
4 : 8 : 4
Shaded part of W : Shaded part of Y
2 : 3
Total shaded area
= 2 u + 1 u
= 3 u
3 u = 24
1 u = 24 ÷ 3 = 8
Area of the whole figure
= 2 u + 8 u + 3 u
= 13 u
= 13 x 8
= 104 cm
2 Answer(s): 104 cm
2