1. (15 points) The number of yeast cells in a laboratory culture increases rapidly initially but levels off eventually. The population is modeled by the function 140 n: f(t)=1+6e'0-7t where t is measured in hours. (a) Find the total change in the bacteria population between t = 2 hours and t = 4 hours. Give proper units (b) Find the average rate on change in the bacteria population between t = 2 hours and t = 4 hours. Give proper units (c) Find the instantaneous rate on change in the bacteria population at t = 3 hours. Give proper units