There are 10 spaces on the spinner, 3 of which are purple (corresponding to the TreeHuggers campaign). So the probability of the TreeHuggers getting a check is 3/10 = 0.30; multiply this probability by the total number of checks to get 0.30*20 = 6. So we expect about 6 checks to go to this organization. This is a theoretical estimate and not always the true empirical value.
