The Pmf for X = the Number of Major Defects $$\begin{array} { l c c c c c } \hline x & 0 & 1 & 2 & 3 & 4 \\\hline P ( x ) & .10 & .15 & .45 & .25 & .05 \\\hline\end{array}$$

Essay

The pmf for X = the number of major defects on a randomly selected gas stove of a certain type is $$\begin{array} { l c c c c c } \hline x & 0 & 1 & 2 & 3 & 4 \\\hline P ( x ) & .10 & .15 & .45 & .25 & .05 \\\hline\end{array}$$ Compute the following:
a. E(X)
b. V(X) directly from the definition
c The standard deviation of X
d. V(X) using the shortcut formula