Answer
$μ_X=3.864$ sets.
In a randomly selected Wimbledon men's single final match, we would expect to observe 3.864 sets played.
Work Step by Step
$μ_X=Σ[x.P(x)]=3\times P(3)+4\times P(4)+5\times P(5)=3\times0,4318+4\times0,2727+5\times0,2955=3.864$
