The population of a town has approximately doubled every 17 years since 1950.
the equation P=
 where Po is the population of the town in 1950, is used to model the population, P, of the town t years after 1950.
When t=17 yrs
 P=2
 
for 1 year
The equation becomes
P = 
 -------------(1)
Our original equation is 
----------------------------------(2)
equating expression 1 and 2

Cancelling 
 from both sides we get

t/17=k
⇒k=t/17 is the solution.