Which of these go with each other?

Can somebody me out with this question

Acertain population of bacteria demonstrates exponential growth doubles in size every 4 days. how long will it take the population to triple in size?

11. a particular type of cell doubles in number every hour. which function can be used to find the number of cells present at the end of h hours if there are initially 4 of these cells? a. n = 4 ()" b. n = 4(2)" c. n = 4 + (2)" din = 4 +"