Distribution patterns and population size

Lemna minor, a species of duckweed, can reproduce to form new plants very quickly. Suppose that a small backyard pond contains 25 Lemna minor plants, and the expected growth rate of the population is 1.0 X 10^2 plants per day. Predict how many Lemna minor plants the pond will contain after 31 days

I seen the link to this but it doesn't make sense so if someone could explain this would be great!!
Plus this lab 20.1 and complete numbers #2-5 ( problem I have here is I counted wayyyyy more moose then how someone has it in the other link) again much help I have to submit this ASAP!!!