The mean (μ) of a discrete random variable (z) is calculated as follows:
[tex]\mu=\Sigma z\cdot P(z)[/tex]Substituting with data:
[tex]\begin{gathered} \mu=-11\cdot0.06-10\cdot0.36-9\cdot0.43-8\cdot0.03-7\cdot0.02-6\cdot0.1 \\ \mu=-0.66-3.6-3.87-0.24-0.14-0.6 \\ \mu=-9.11 \end{gathered}[/tex]