Culture in petri dish A is 1.08 x 10^15 and culture in petri dish B is 2.7 X 10^11. To determine how much greater petri dish A is from petri dish b, you must divide petri dish A by petri dish b. When you divide the two numbers, the answer is 4,000. The number of bacteria in petri dish A is four thousand times greater than the number of bacteria in petri dish B.