q + q q p = 3pq2
P(X = 2) = P (two successes)
= P({SSF, SFS, FSS})
= P({SSF}) + P ({SFS}) + P({FSS})
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MATHEMATICS
= P(S) P(S) P(F) + P(S) P(F) P(S) + P(F) P(S) P(S)
= p p