Acountry's population in 1991 was 59 million. in 2000 it was 63 million. estimate the population in 2009 using the exponential growth formula.

According to this, it grows by 4 million every 9 years, so it would be 67 million in 2009

Ok so the formula for grouth is
A=Pe^(kt)
a=amount future
P=present amount
k=constant
t=time

we have

it grew from 59 million to 63 million
in 9 years
A=63
P=59
t=9

so
63=59e^(k9)
divide both sides by 59
(63/59)=e^(9k)
take ln both sides
ln(63/59)=9k
divide both sides by 9
(ln(63/59))/9=k
evaluate with calulator and save that value

so now we need 2009

after t years

2009-1991=18 years
t=18
P=59
k=ans
find A
A=59e^(ans18)
A=67.27118
about 67 million
find k