Given : The population of a city in 2005 was 18,000. By 2010, the city’s population had grown to 45,000 .
Any exponential growth is represented by the formula y= a

a is the initial population y is the final population .t represents the number of years.
Substituting the values :
45000 = 18000

Solving for b
b=1.2
Number of years from 2005 to 2015 is 5 years.
Y= 45000

y= 111974.4
Population in 2015 is 111974.