Question

A city has the population of 350,000 persons the population has decreased by 30% in the past 10 years what is the population of the city 10 years ago

Answer 1

As per the statement: A city has the population of 350,000 persons the population has decreased by 30% in the past 10 years.

The formula for calculating the percent change between two values over the time is given by:

`p = (A-B)/(B) * 100`

where

p represents the percent change

A represents the New value

B represents the Old value

Since, p is the percent(decreased) = -30

Substitute the given values and solve for B;

then;

`-30= (350000-B)/(B) * 100`

Divide both sides by 100 we get;

`-0.3 = (350000-B)/(B)`

By cross multiply we get;

`-0.3B = 350000-B`

Add both sides B we get;

`-0.3B+B = 350000`

`0.7B = 350000`

Divide both sides by 0.7 we get;

B = 500,000

Therefore, the population of city 10 years ago before 305 decrease in population was 500,000