Population growth rate?

P = 6,741,727,032 (1.01167)^t , t = number of years

now it's easy to do A/ B/

5.) On December 6, 2008, the world's population was estimated to be 6,741,727,032. If the

growth rate is 1.167% per year, answer the following. 

A.) When will the world's population reach 10 billion?

t = ln(N/N0)/r (time)

N = 10,000,000,000 future population

N0 = 6,741,727,032 initial population

r = 0.01167 growth rate per year (as a decimal)

t = ln(10,000,000,000/6,741,727032)/0.01167

t = 33.78 years

Year of 10 billion = 2042 A.D.

B.) By what year will the population double?

 N = 13,483,454,064 future doubled population

t = 59.40 years

Year of Doubling = 2067 A.D.