A computer is used to pick three letters, one after the other from (A, B). Each letter can be picked more than once and has the same chance of being selected. The possible outcomes for this experiment are given in this table:

AAA, AAB, ABA, BAA
BBA, ABA, BAB, BBB

P(A then B then A) 0.125, 0.250, 0.375, 0.500, 0.625