question_answer

A number is increased by 20% and then it is decreased by 20%. Find the net increase or decrease per cent.

Answer:

Let the number be 100

Increase in the number = 20% of 100 =20

So,       increased number = 100 + 20 = 120

Decrease in the number = 20% of 120

\[=\frac{20}{100}\times 120=24\]

So,  new number \[=\text{ }120\text{ }-\text{ }24\text{ }=\text{ }96\]

Net  decrease \[=\text{ }100\text{ }-\text{ }96\text{ }=\text{ }4\]

Hence,   net decrease per cent

\[=\frac{4}{100}\times 100=4%\]