UPSC CDS 2 2020 Math Paper

Assuming length is denoted by L
And breadth by b.
Then initial area of rectangle = L.b
But as given condition final length (L’) = 1.1L …………..(10% increase).
Final breadth (b’) = 0.9b …………..(10% decrease) .
Hence final area of the rectangle = L’.b’
=1.1L×0.9b
=0.99Lb
Thus it is 1% less than initial area.