I would have to assume that the correct form of the formula is:
f(x) = 14,600(1.1)^x
where x is time in years and is an exponent of (1.1)
Since we are finding for the original population, therefore x = 0
f(x) = 14,600 (1.1)^0
Any number raised to the power of 0 is just equal to 1. Therefore:
f(x) = 14,600
The original population is 14,600.
