There are 25 species of trees, each with a known abundances. The question is how many possible ways to randomly select one tree there are. We should calculate the number of combinations. Combinations, because we select item/s from a collection. In this case, when we select only one item, the combination is also a permutation. From set of n objects we select r. In our case: n=25, r=1. The equation is: n!/r!(n-r)!= 25!/1!*24!=25*24!/24!=25 There are 25 different outcomes (events).
