A cylindrical tank with a cross-sectional area of 100 cm² is filled to a depth of 100 cm with water. At t = 0, a drain in the bottom of the tank with an area of 10 cm² is opened, allowing water to flow out of the tank. The depth of water in the tank at time t ≥ 0 is d(t) = (10 - 2.2t)².

a. Check that d(0) = 100, as specified.

b. At what time is the tank empty?

c. What is an appropriate domain for d?