In a city in year 1990 have lived 700000 residents while in year 2000 there were 900000 residents
If you take the growth in population made at the same rate , find :
a) how much is the population grow of the city in the time period 1990-2000 ?
b) how much became the population number this year(2009) ?
c) when will the city have 1400000?
If the title is assumed to be correct then you can use the general formula for a geometric sequence
Using the sum of a geometric sequence:
If you set 1990 as n=0 then in 2000: n = 2000-1990. Setting 1990 as 0 will also give you a value of a from which the common ratio r can be found