This exercise uses the population growth model. A certain culture of the bacterium Rhodobacter sphaeroides initially has 25 bacteria and is observed to double every 4 hours.

(a) Find an exponential model n(t) = n₀2^t/a for the number of bacteria in the culture after t hours.

n(t) =

(b) Estimate the number of bacteria after 18 hours. (Round your answer to the nearest whole number.)

(c) After how many hours will the bacteria count reach 1 million? (Round your answer to one decimal place.) t =