For each subset it can either contain or not contain an element. For each element, there are 2 possibilities. Multiplying these together we get 27 or 128 subsets. For generalisation the total number of subsets of a set containing n elements is 2 to the power n.
She has totally 10+5+3=18 marbles, so the probability is 10/18=5/9. The complement is (9-5)/9=4/9.
Hope this helped!
The equation that models the difference in the projected enrollments for
public schools and private schools as a function of the number of years
since 1985 is B - R = (-18.53t^2 + 975.8t + 48140) - (80.8t + 8049) = -18.53t^2 + 975.8t + 48140 - 80.8t - 8049 = -18.53t^2 + 895t + 40091
The domain is y >=0. Domain is the possible x values
