Question

This exercise uses the population growth model.

The population of the world was 7.1 billion in 2013, and the observed relative growth rate was 1.1% per year.

(a) Estimate how long it takes the population to double. (Round your answer to two decimal places.)

(b) Estimate how long it takes the population to triple. (Round your answer to two decimal places.)

Answer 1

The population of 7.1 billion is irrelevant in this problem
For doubling at 1.1%
(1 + .011)^n = 2
1.011^n = 2

a) your question says to estimate, and then asks for 2 decimal accuracy, which makes no sense.
anyhow.....
take log of both sides:
log (1.011^n) = log2
n log 1.011 = log 2
n = log2/log 1.011 = 63.36 years

for b, use the same steps in
1.011^t = 3