The depth of water in a certain uniform cylinder is given by the depth vs. clock time function y = .021 t² + -1.1 t + 79.  

What is the average rate at which depth changes between clock times t = 6.2 and t = 12.4?

• What is the clock time halfway between t = 6.2 and t = 12.4, and what is the rate of depth change at this instant?
• What function represents the rate r of depth change at clock time t?
• What is the value of this function at the clock time halfway between t = 6.2 and t = 12.4?

If the rate of depth change is given by dy/dt = .133 t + -1 then how much depth change will there be between clock times t = 6.2 and t = 12.4?

• Give the function that represents the depth.
• Give the specific function corresponding to depth 190 at clock time t = 0.