a private opinion poll is conducted for a politician to determine what proportion of the population favors adding more national parks. what size sample should be obtained in order to be 98confident that the sample proportion will not differ from the true proportion by more than 3% you sent assume that the heights of bookcases are normally distributeda random sample of 16 bookcases in one company have a mean height of 67.5 inches and a standard deviation of 2.4 inches . construct a 99% confidence interval for the population standard deviation you sent find the t-value such that the area left of the tvalue is 0.001 with 15 degrees of freedom. you sent what is the probability associated with not making a type error? you sent determine the critical value z alpha l2 that corresponds to the given level of confidence. you sent determine the critical value for a left-tailed test of a population standard deviation for a sample of size n