Answer:
64
Explanation:
ASSUMING WE STARTED WITH ONE BACTERIA
there are 3 20 minute marks in an hour.
3 x 2 = 6
So are going to do the following
1 x 2 = 2
2 x 2 = 4
4 x 2 = 8
8 x 2 = 16
16 x 2 = 32
32 x 2 = 64
...
So in two hours a bacteria that increases two times every twenty minutes would multiply into sixtyfour bacteria in 2 hours.