On the first day of the year (t = 0), a city uses electricity at a rate of 2000 MW. That rate is projected to increase at a rate of 1.3% per year. 

a. Based on these figures, find an exponential growth function for the power (rate of electricity use) for the city.

b. Find the total energy (in MW-yr) used by the city over four full years beginning at t = 0.

c. Find a function that gives the total energy used (in MW-yr) between t = 0 and any future time t > 0.