Ex.8.3 Q3 Compairing Quantities - NCERT Maths Class 7

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Question

The population of a city decreased from \(25,000\) to \(24,500.\) Find the percentage decrease.

Text Solution

What is Known?

The change in the population of a city (from \(25,000\) to \(24,500\))

What is Unknown?

The percentage decrease

Reasoning:

The decrease in population can be calculated by subtracting earlier (initial) population from present (final) population and percentage decrease in population can be obtained using the formula

 Percentage decrease   

\[\begin{align}=\frac{{{\text{Change}}\;{\text{in}}\;\;{\text{quantity}}}}{{{\text{Initial}}\;{\text{quantity}}\;}}{\rm{ \times 100}}\end{align}\]

Steps:

 Decrase in city population 

\[\begin{align}&= 25000 - 24500\\&= 500\end{align}\]

Percentage decrease 

\[\begin{align}&= \,\frac{{{\text{Change}}\;{\text{in}}\;\;{\text{population}}}}{{{\text{Initial}}\;{\text{population}}\;}}{\rm{ \times 100}}\\&= \,\frac{{{\text{500}}}}{{{\text{25000}}}}{\rm{ \times 100}}\\&= \,{\text{2% }}\end{align}\]