If a tank holds 5000 gallons of water, which drains from the bttomof the tank in 40 minutes, then torricelli's Law gives the volume Vof water remaining in the tank after t minutes $(1-{\frac{t}{40}}^{2})5000=V0\le t\le 40$.

Find the rate at which water is draining from the tank after (a) 5min, (b) 10 min. At what time is the water flowing out the fastest?the slowest?