Question

If the population of a country increases at a rate of 1.5%  annually, and its current population is 430,000, how many years will it take for the population to triple?

 A 2 years   B 150 years    C 73 years or   D 3 years

Answer 1

For this case we have an equation of the form:

`y = A * (b) ^ t`
Where,
A: initial amount
b: growth rate
t: time in years.
Substituting values we have:

`y = 430000 * (1,015) ^ t`
By the time the population is triple we have:

`3 * 430000 = 430000 * (1,015) ^ t`
Rewriting we have:

`3 = (1,015) ^ t`
Clearing t we have:

`t = log1.015 (3) t = 73.78876233 t = 73 years`
Answer:
It will take for the population to triple about:
t = 73 years