1. .

a) Variance represents the average of the squared difference from the mean. Variance 0 means all values are same as mean which indicates identical values. Thus the statement is true.

b) As there is no common region between A and Ac so P(A and Ac) 0 and thus the given statement is false.

c) As the normal distribution is symmetric about the mean so the mean and median is the same value and thus the given statement is true.

d) For 99% confidence interval we need a larger Z or t-value (or any other value as appropriate) to multiply with standard error to find out the confidence interval. Thus the statement is correct.

e) Smaller significance level gives larger critical value and hence rejecting the null hypothesis becomes more difficult so the given statement is false.

1. The...