For a population that has a standard deviation of 20, figure the 95% confidence interval (that is, the lower and upper confidence limits) for parts (a) through (d). Assume that in each case the researcher's sample has a mean of 101 and that the population of individuals is known to follow a normal curve. . . . (a) Figure the 95% confidence interval for samples of size 3. One can be 95% confident that the true population mean is between 78.37 and 123.63 . (Type integers or decimals rounded to two decimal places as needed.) (b) Figure the 95% confidence interval for samples of size 4. One can be 95% confident that the true population mean is between and (Type integers or decimals rounded to two decimal places as needed.)