Population

In 1999 there are two countries A and B . the population of contry A is 20 million and that of country B is 40 million. country A is a rich country and has experinced an exponential population growth of 5 % per year while country B is a poor country and has experienced an exponential population shrink of 5% per year. In how many years will the two countries reach the same number of population ?

If the number of population reached (per million ) is N and the number of years is T then find N + T. to two decimal places.

notations :

• Assume the rate of population change is directly proportional to the population itself.

• ln2 = 0.693147

• √2 = 1.4142