Advance functions

On Jan 1, 10 workers in factory had malaria virus and the number of people affected is doubling everyday.
a)—write a function V(t) where V is the number of people infected and t is the time, in days since Jan 1.
-use the function to determine the number of people infected after 6 days

b)—determine the average rate of change for V(t) between Jan 3 and Jan 4

c) ---If there are 1525 people in the factory, approx. how many days will it take until everyone is infected with the virus?
Note-round to 1 decimal place