QUESTION 1 Assume a sample of size 40 is taken from a population with unknown distribution. Which of the following is an unbiased estimator for population mean, ,u '? 0 sample mean, 11 0 population variance, 62 0 sample variance, 32 0 sample standard deviation, s QUESTION 2 Assume a sample of size 20 is taken from a population with known normal distribution. Which of the following is an unbiased estimator for population variance, 02 '? 0 sample mean, x 0 sample standard deviation, S 2. 0 sample variance, 3 0 population mean, Ju QUESTION 3 Assume a sample is taken from a population with unknown distribution. Which of the following is the most efficient unbiased estimator among the choices given for population mean, Ju ? 0 sample mean, ;, for sample of size 40 0 sample mean, ;, for sample of size 100 0 sample variance, 32, for sample of size 50 0 sample variance, 5'2, for sample of size 200