(1 point) A bacteria culture starts with 900 bacteria and grows at a rate proportional to its size P(t). After 5 hours there are 6000 bacteria. (a) Find an expression for the number of bacteria after t hours. P(1) = (b) Find the number of bacteria after 6 hours. P(6) = bacteria (c) Find the growth rate after 6 hours. P' (6) = bacteria/hour (d) After how many hours will the population reach 30000? hours =