一條數學help me

twenty four people had a blood test and the results are shown below.

A.B.B.AB.AB.B.O.O.AB.O.B.A
AB,A,O,O,AB,B,O,A,AB,O,B,A

(a) construct a frequency distribution for the date.
(b)if a person is selected randomly from the group of twenty four people.
what is the probability that his/her blood type is not O ?