Question 62314
We know the formula 

The Extra population is given by =  Present population *  rate of the population * time in 
years

Extra population = 3000 * 0.6 * t

Now population after t years is given  = 3000 + 3000 * 0.6 * t

p(t) = 3000 + 1800t

Therefore the function p(t)=  3000 + 1800t