How do I start this?

Question

The population of a small town doubled every 10 years from 1960 to 1990.  What was the percent increase in population during that time period?

Answer 1

The population doubled every ten years.

 

For instance, if there were only 10 people in 1960, there would be 20 people by 1970. (number multiplied by 2)

 

if there were 20 people in 1970 then there would be 40 people in 1980. (again, multiplied by 2)

 

Do you see a pattern?

 

Let x = number of people in 1960

 

1960: x

1970: 2x

1980: 2(2x) = 4x

1990: 2(4x) = 8x

 

By 1990 there are 8 times as many people as 1960 which is an 800% increase.