Question

A population of geese grow in such a way that each generation is simply 2.2 times the previous generation. There were 3 geese in the first generation, how many will there be by the 15th generation?

Answer 1

 186,655 that's the answer

Answer 2

First generation: 3

Second generation: $3\times2.2$

Third generation: $3\times2.2\times2.2=3\times2.2^2$

Fourth generation: $3\times2.2\times2.2\times2.2=3\times2.2^3$

And so on. The general formula for the $n$th generation is $3\times2.2^{n-1}$. So by the 15th generation, you should expect around $3\times2.2^{15-1}\approx186655$ geese.