UPSC Civil Services 2014 Prelims General Studies Paper II

Let initial dimensions be, l & b
∴ Final length is 1.4 l
Final breadth is 0.8 b
∴ Final area is = 1.4 l × 0.8 b = 1.12 lb
∴ Area is increased by 12%.
Shortcut Method: +40−20+

40×(−20)

100

=20−8=12%
Therefore, the area of the new garden increased by 12%