Water is poured into a container that has a leak.The
mass 'm' of the water is given as a function of time 't'
by, m=5t^0.8 -3t + 20 , with t>=0, mass in grams and t in seconds

a. at what time is the water mass greatest,and
b. what is the greatest mass? In kilogram per minute what is the rate of mass change at t=3 s, and t=5 s.