`E(X)`

`=sum{x_i*P(x_i)}`

`=1times0.34+2times0.44` `+3times0.11+4times0.06` `+5times0.02+6times0.01` `+7times0.01+8times0.01`

`=2.1`

So the average family size is E(X) = μ = 2.1 people.

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