Question. The number of flaws $X$ on an electroplated car grill is known to the have the following probability mass function: $ \begin{matrix} x & : & 0 & 1 & 2 & 3 \\ p(x) & : & 0.8 & 0.1 & 0.05 & 0.05 \end{matrix} $
Calculate the mean of $X$.
My working.
$ \text{Mean} = E(X) = (0 \times 0.8) + (1 \times 0.1) + (2 \times 0.05) + (3 \times 0.05) = 0.35 .$
But the answer is $0.25$ (which is also $\frac{0.8+0.1+0.05+0.05}{4}$).
What am I doing wrong?