Question

The population of a certain country is expected to double every 32 years. The population of this country was 4.2 million people in the year 2000. To the nearest tenth of a present, by which percentage rate is the population expected to increase each year

Answer 1

2.2%

Explanation:

Given the following :

Population in year 2000 (A) = 4.2 million

Expected population every 32 years = 2 *A

The growth rate per year =?

The population figure after 32 years = (2 * 4.2 million) = 8.4 million

Using the exponential growth formula :

P(t) = A × (1 + r)^t

(1 + r) = g = Total growth percent

A = Initial population

t = time

P(t) = 8.4 million

8,400,000 = 4,200,000 × g^32

g^32 = (8400000/4200000)

g^32 = 2

Taking the root of 32 on both sides

g = 1.02189714865

g = (1 + r)

1.02189714865 = 1 + r

r = 1.02189714865 - 1

r = 0.02189714865

.rate = 0.02189714865 * 100

= 2.18971486541%

= 2.2% ( nearest tenth)