Question

5 percent decrease every year of 690 and the rate continues, find the number in 5 years

Answer 1

Population after 5 years = 534

Solution:

Given population, P = 690

Rate decrease, R = 5%

Number of years, n = 5

If the population decrease constantly R% , then the population after n years is

`P(1-(R)/(100) )^n`

Substitute the given values in the above formula.

`P(1-(R)/(100) )^n=690(1-(5)/(100))^5`

Cross multiply 1 and 100 to get the same denominator.

`=690((100-5)/(100))^5`

`=690((95)/(100))^5`

`=690((19)/(20))^5`

= 533.90

= 534

Hence the population after 5 years is 534.