Answer:
450 Bacteria
Explanation:
First we need to consider the amount of bacteria that grew after two hours. Since 100 bacteria grew after 2 hours, we need to find how much bacteria grows per hour.
We can find that by dividing 100 by 2
100/2 = 50 Bacteria per hour
Now that we know how much bacteria grows per hour, we can then multiply that amount to the amount of hours asked in the problem.
9 hours x 50 Bacteria = 450 Bacteria in 9 hours.