Approximately one-third of all human twins are identical (one-egg) and two-thirds are fraternal (two-egg) twins. Identical twins are necessarily the same sex, with male and female being equally likely. Among fraternal twins, approximately one-fourth are both female, one-fourth are both male, and half are one male and one female. Finally, among all U.S. births, approximately 1 in 90 is a twin birth. Define the following events:
A = (a U.S. birth results in twin females}
B = {a U.S. birth results in identical twins}
C = (a U.S. birth results in twins}
(a) State, in words, the event A ∩ B ∩ C.
(b) Find P(A∩B∩C).