The Random Variable X Represents the Number of Credit Cards

Multiple Choice

The random variable x represents the number of credit cards that adults have along with the corresponding probabilities. Find the mean and standard deviation. $$\begin{array} { c | c } \mathrm { x } & \mathrm { P } ( \mathrm { x } ) \\\hline 0 & 0.07 \\1 & 0.68 \\2 & 0.21 \\3 & 0.03 \\4 & 0.01\end{array}$$

A) mean: 1.23; standard deviation: 0.66
B) mean: 1.30; standard deviation: 0.32
C) mean: 1.30; standard deviation: 0.44
D) mean: 1.23; standard deviation: 0.44