Hello. I have a few questions I am having trouble with.

12. A bacterium has 25 cells, and in 10 hours grow to 350. What is the doubling period of the bacteria? Use the formula y=c(a)^t/d

13. In 1990, at t=0, the population of a city was 48 500. In the year 2000, its population was 50 000. If the population grows exponentially, find the groth rate using the formula P=k(a)^t