The rectangle is divided into four parts J, K, L and M. The ratio of Part J to Part K is 7 : 4 and the ratio of Part K to Part L is 4 : 1.
- Find the ratio of Part J to Part K to Part L.
- Given that Part M is 60 cm2 , find the area of the rectangle.
(a)
| J |
K |
L |
M |
| 7x1 |
4x1 |
|
|
| |
4x1 |
1x1 |
|
| 7 u |
4 u |
1 u |
60 cm2 |
Part K is the repeated identity.
LCM of 4 and 4 = 4
Part J : Part K : Part L = 7 : 4 : 1
(b)
Part J + Part K = Half of the rectangle
Part L + Part M = Half of the rectangle
Part J + Part K and Part L + Part M are equal.
Part J + Part K = Part L + Part M
7 u + 4 u = 1 u + 60
7 u + 4 u - 1 u = 60
10 u = 60
1 u = 60 ÷ 10 = 6
Area of the rectangle
= 2 x (1 u + 60)
= 2 x (1 x 6 + 60)
= 2 x (6 + 60)
= 2 x 66
= 132 cm
2 Answer(s): (a) 7 : 4 : 1; (b) 132 cm
2 
