Answer
$μ_X=2.519$
If we randomly select a large number of parents of a 6th- to 8th-grade, we would expect to find them involved in about 2.519 activities of their children.
Work Step by Step
$μ_X=Σ[x.P(x)]=0\times P(0)+1\times P(1)+2\times P(2)+3\times P(3)+4\times P(4)=0\times0.073+1\times0.117+2\times0.258+3\times0.322+4\times0.230=2.519$
