How to solve a-d?

7. [-/3.75 Points] DETAILS FDPRECALC5 5.4.003." MY NOTES The bacteria in a culture increased from 400 at 1:00 P.M. to 3200 at 6:00 P.M. (a) Find the expression for the number of bacteria t hours after 1:00 P.M. Q (t ) = (b) Find the number of bacteria that will be present at 7:00 P.M. (Round your answer to the nearest whole number.) bacteria (c) When will the population reach 12,000? (Round your answer to one decimal place.) hr (d) How long does it take the population to double in size? (Round your answer to one decimal place.) hr