Question

Amar drew a square. He then erased it and drew a second square whose sides were $3$ times the sides of the first square. By what percent was the area of the square increased?

• A. $200\%$
• B. $400\%$
• C. $600\%$
• D. $800\%$

Answer 1

Answer: (D)

$800\%$

Let side of the square = $a$

Area = $a^2$

$\therefore$ new side = $3a$

Hence, new area = $(3a{)}^2=9a^2$

Precentage increase in area = $\frac{9a^2-a^2}{a^2}\times 100=800\%$