Answer: There will be a number of 25600 bacteria after 2 hours.
Explanation: This problem requires some simple math to solve.
We were told that E. coli doubles approximately every 15 minutes. Meaning that, after just 15 minutes, our colony of 100 bacteria is now a colony of 200 bacteria and so forth:
100 * 2^1 = 200
There are 4 15-minute periods in an hour, thus there are 8 15-minute periods in two hours. Therefore, the bacteria will have doubled their population size 8 times:
100 * 2^8 = 25,600
