Hello,

Consider the function x(t) the number of inhabitants and t the number of years.

For the first year, 200000 becomes 200000*(100+1.5)/100

For the second year, the population becomes 200000*(100+1.5)/100 *(100+1.5)/100 = 200000*((100+1.5)/100)²

And so on... Each year, you multiply the number of inhabitants by (100+1.5)/100 (corresponds to an augmentation of 1.5%)

So x(t)=200000*(101.5/100)^t

And you want t such as x(t)>250,000

Hence the problem is to solve 200000*(101.5/100)^t > 250000