Given that Americans of Mexican ancestry constitute 80 % of the population, it is noted that during a period of 11 years, 870 people were selected for duty on a grand jury.
a) Assuming that groups of 870 grand jurors are randomly selected, find the mean and standard deviation for the numbers of Mexican Americans
b) Use the "rule of thumb" to find the minimum usual number and the maximum usual number of Mexican-americans. Based on those numbers, discuss whether we can conclude that the actual result of 339 mexican-americans is unusual. Does this suggest that the selection process discriminat4ed against Mexican-americans?