Do each of the following:
a) What is the minimum number of people that must be in a room
to guarantee that at least 20 were born on the same day of the
week? Assume all days of the week are equally likely.
b) What is the coefficient of x 9 y 11in ( 3 x − 4 y ) 20?
c) What is the probability that in a permutation of the letters
{A, B, C, D, E, F, G,...