Question

A number is increased by $40\%$ and then decreased by $40\%$. Find the net increase or decrease per cent.

• A. $16\%$
• B. $20\%$
• C. $10\%$
• D. $32\%$

Answer 1

The correct option is A $16\%$

Let the number be $100$.
Increase in the number $=40\%=40\%$ of $100=\frac{40}{100}\times 100=40$

Therefore, increased number $=100+40=140$

This number is decreased by $40\%$

Therefore, decrease in number $=40\%$ of $140=\frac{40}{100}\times 140=\frac{5600}{100}=56$

Therefore, new number $=140-56=84$

Thus, net decreases $=100-84=16$

Hence, net percentage decrease $=\frac{16}{100}\times 100=16\%$