True or False. Justify for full credit.
(a) If the variance of a data set is zero, then all the observations in this data set are zero.(b) If P(A) = 0.4 , P
(B) = 0.5, and A and B are disjoint, then P(A AND B) = 0.9.
(c) A 95% confidence interval is wider than a 90% confidence interval of thesame parameter.