The population of goats on a particular nature reserve t years after the initial population was sett

The population of goats on a particular nature reserve t years after the initial population was settled is modeled by p(t) = 4000 - 3000e^-0.2t. How many goats were initially present?

Initially present means at time 0. Substituting t = 0, p(0), we get:
p(0) = 4000 - 3000e^-0.2(0)
p(0) = 4000 - 3000e^0
p(0) = 4000 - 3000(1)
p(0) = 4000 - 3000
p(0) = 1000