CDS 2015 PYQ with Answer — ABCD is a square. If the sides AB and CD are increased by 30%, sides…

2015 · Q72

ABCD is a square. If the sides AB and CD are increased by 30%, sides BC and AD are increased by 20%, then the area of the resulting rectangle exceeds the area of the square by

Elementary MathematicsMensuration

A50%
B52%
C54%
D56%

Explanation

This tests successive percentage increase applied to area. The sides become 1.30 and 1.20 times their originals, so the area scales by 1.30 × 1.20 = 1.56 — a 56% increase. The trap is option (a) 50%, from adding 30 + 20; percentage changes on two dimensions multiply, they do not add. Hence option (d).