Answers by visitors named: Erim
Thats super simple you just gotta plug the information into a compound-interest formula.
Number of bacteria after 2 hours = Original amount(1 + % of increase)^to the power of rate of increase
So in this case:
N = 100(1+1)^6
Since they reproduce every twenty minutes, in two hours they'll reproduce 6 times
The answer is 6400