Question 968704
a.For the population to double we have 100(1.04)^x=200
  (1.04)^x=2
  Taking logarithm on both sides to base 10 we get,
  x log(1.04)=log2
  x=log2/log(1.04)=17.67 years
 It will double in 17.67 years.
b.For the population to become 1000 we have 100(1.04)^x=1000
  (1.04)^x=10
  Taking logarithm on both sides to base 10 we get,
  x log(1.04)=log 10
  x log(1.04)=1
  x=1/log(1.04)=58.708 years.
  It will become 1000 in 58.708 years.