Question

the population of a country increased in 10 years at an average rate of 5% p.a. if the average rate of increase during the first 6 years is 3% p.a., find the average rate of increase in the next four years.

Answer 1

Explanation:

x = population now

In 10 years pop = x (1.05)^10 <=====average

in 6 years pop is x(1.03)^6

then use this pop for the unknown increase for 4 years

x ( 1.03)^6 (1+ if)^4

x ( 1 +.05)^10 = x ( 1+.03)^6 (1+if)^4 you can eliminate 'x' and solve for if ( i four years)

1.05^10 =( 1.03)^6 (1+if)^4

.43484 = (1+if)^4

if = 8.07 % for last four years