A variable of two populations has mean of 7.9 and standard deviation of 5.4 for one of the populations and a mean of 7.1 and standard deviation of 4.6 for other population.
(a) For independent samples of 3 and 6, respectively, determine the mean and standard devriation of x1 and x2.
(b) Must the variable under consideration be normally distributed upon each of two populations for your to answer part (a)? Discuss your answer.
(c) Can you conclude that variable x1 minus x2 is normally distributed? Explain your answer.