Given :
The population of a small town is 47,288 and has been continuously declining at a rate of 2.4% each year.
To Find :
The approximate population of the town in 21 years.
Solution :
Let, new population after x years is P.
So, P is given by :
[tex]P = 47288\times ( 1- 0.024)^x\\\\P = 47288\times (0.976)^x[/tex]
Now, putting value of x = 21 in above equation, we get :
[tex]P = 47288\times (0.976)^{21}\\\\P = 28392[/tex]
Therefore, option d) is correct.