Question

Question #dba1a

Answer 1

The population 2 years hence was 2000 people.

Explanation:

For each year, the end population is 90% of the starting population (100%). That means that:
`1620=90%`
and
`x=100%`

So, to know the population from a year ago, we have to set up the following equality:
`1620/x=90/100`

Now, with a little algebra we do the following steps to single out `x`"

1) multiply each side by `x`
`cancel(x)*1620/cancel(x)=90/100*x`

2) multiply each side by 100
`100*1620=x*90/cancel(100)*cancel(100)`

3) multiply each side by `1/90`
`1/90*100*1620=x*cancel(90)*1/cancel(90)`

Leaving us with:
`x=(100*1620)/90` which is equal to `1800`

Now if we do the same process with 1800 to start with, we get the final equation:
`x=(100*1800)/90` which is equal to `2000`