Problem E: An inverted conical water tank has a height of l feet and a radius of 4 . It is being drained at a rate of 2 3fs. How fast is the water level changing when the water depth is 3 H? [The volume of a IIII'IE is V =r2h1 [ll] paints} \fProblem 3 Show that the functin f[:r] = x3\" 2 has exactly one real root. (10' points]