omework Part 3 of 3 Points: 0.33 of 1 Let P(t) be the population (in millions) of a certain city t years after 1990, and suppose that P(t) satisfies the differential equation P' = .04P(t), P(0)=4. (a) Find the formula for P(t). P(t) = 40.041 (Type an expression using t as the variable.) (b) What was the initial population, that is, the population in 1990? The initial population was 4 million. (c) Estimate the population in 1998. The population in 1998 was million. (Round to two decimal places as needed.))