Supplementary Exercise 4.26 of IPS7e
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Simple random sample (SRS) of 2 persons from a group of 5 persons,
abbreviated in the following by the first letter:
Abby (A), Deborah (D), Mei-Ling (M), Sam (S), Roberto (R).

(a) S = {(A,D),(A,M),(A,S),(A,R),(D,M),(D,S),(D,R),(M,S),(M,R),(S,R)}

(b) each outcome has probability 1/k = 1/10 (the sample space has
k=10 elements); this is called a uniform distribution.

(c) P(M chosen) = 4/10 = 0.4 (M is present in 4 of the 10 outcomes)

An additional (optional) probability argument for this value is the following:
  P(M not chosen) = 4/5 * 3/4 = 3/5 = 0.6 (similar to birthday party problem)
  P(M chosen) = 1 - P(M not chosen) = 0.4

(d) P(neither of S and R chosen) = 3/10 = 0.3 (3 of the outcomes apply)

By a similar probability reasoning as above:
  P(neither of S and R chosen) = 3/5 * 2/4 = 3/10.