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 female and male being equally...

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 female and male being equally likely. Among fraternal twins, approximately one-fourth are both female, one-fourth are both male, and half are one female and one male. Finally, among all births in the
United States, approximately 15 in 1000 are twin births.

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}

1. 
   Find P(A ∩ B)
   


2. 
   Find P(A ∩ C).
   


3. 
   Find P(B ∩ C).
   


4. 
   Which event is pairwise independent?