The random variable x is the number of houses sold by a realtor in a single month at the real-estate office. Its probability distribution is:
Houses sold (x) Probability P(x)
0 0.09
1 0.24
2 0.21
3 0.17
4 0.03
5 0.15
6 0.09
7 0.02
a. Compute the mean of the random variable.
b. Compute the standard deviation of the random variable.