Given that population of the city is 280000.
Rate of growth of the population = r = 4.5% = 0.045
We have to find population after 15 years so time
t = 15
We can use growth formula to find the required population which is given by :
Where P= starting population = 280000
r= rate of growth = 0.45
t= time = 15
now plug these values into above formula.
Hence population after 15 years will be approx 73735743.