strain of bacteri doubles in each 20 days.........?

Question

a strain of bacteria doubles in each 20 days. 2 of these are placed on a spaceship & sent away from earth for 1000 earth days.during this time, the speed of ship was 0.9950c. how many bacteria would be aboard when ship lands on earth ? i)128 ii)64 iii)56 iv)28

Answer 1

I really hope that those are not answer choices. If I did it right then there would be 2.252799814*10^15 bacteria on the ship. I am unsure what part the ship speed plays in the problem but since I didnt get any of your choices I assume something went wrong somewhere. The function that would display the growth of the bacteria is 2*2^X.
Hope that helps