A number is increased by 20% and then again by 20%. By what percent should the increased number be reduced so… · ABC26GN2407
Subject: General Aptitude · Chapter: Percentage
A number is increased by 20\% and then again by 20\%. By what percent should the increased number be reduced so as to get back the original number?
(a)$19 \frac{11}{31} \%$
(b)$30 \frac{5}{9} \%$
(c)40\%
(d)44\%
Answer
Answer (as printed): B
Explanation
Let original number = 100. New number = 120\% of 120\% of 100 $$=\left(\frac{120}{100} \times \frac{120}{100} \times 100\right)=144 .$$ Decrease on $144=44$. Decrease on 100 $$=\left(\frac{44}{144} \times 100\right) \%=30 \frac{5}{9} \% .$$
Explanation as extracted from the printed page; notation may be imperfect.