The number of cells in a cell culture grows exponentially. The number of cells in the culture as a function of time is given by the expression N where t is measured in hours and N is the initial N size of the culture. a. After 3 hours, there were 1728 cells in the culture. What is N? b. How many cells were in the culture after 20 minutes? Express your answer in simplest form. c. How many cells were in the culture in 2.5 hours? Express your answer in simplest form