4. (4 pts) Using estimates of rainfall, evaporation, and water consumption, the town engineer developed

the following model of the water volume in the reservoir as a function of time:

V(t) = 10^9 + 10^8 (1 - e-t/100) - rt

Write a function called reservoir (t) to compute the volume in the reservoir as a function of time.

The function should have one argument, time. For r, user = 107 L/day.

a. Plot the volume in the reservoir as a function of time (0 to 100 days; use r= 107 L/day).

b. Use the Scipy fsolve function and your reservoir function to compute how long it will take

until the reservoir is empty. Again, use a value of r = 107 L/day.