An experiment designed to measure the growth of bacteria began at 2:00 P.M. and ended at 8:00 P.M. on the same day. The number of bacteria is given by the function N, where N(t) = 1000 . 3²ᵗ/³ and t represents the number of hours that have elapsed since the experiment began. How many more bacteria were there at the end of the experiment than at the beginning of the experiment?