Find the mean and standard deviation for the numbers of sleepwalkers in groups of five.
Refer to the accompanying table, which describes the numbers of adults in groups of five who reported sleepwalking (based on data from "Prevalence and Comorbidity of Nocturnal Wandering In the U.S. Adult General Population," by Ohayon et al., Neurology, Vol. 78, No. 20).
x P(x)
0........................0.172
1........................0.363
2........................0.306
3........................0.129
4........................0.027
5........................0.002