Question: Let X 1 be a random variable from a distribution with a mean of 8 and a standard deviation of 6, and X 2 be
Let X1 be a random variable from a distribution with a mean of 8 and a standard deviation of 6, and X2 be a random variable from a distribution with a mean of 7 and a standard deviation of 5.
(i) For independent samples of sizes n1 = 3 and n2 = 6, find the mean and standard deviation of x bar1 - x bar2.
(ii) Do X1 and X2 have to be normally distributed for your answer to part (i) to be valid? Explain.
(iii) Can you conclude that the variable x bar1 - x bar2in part (i) is normally distributed? Explain.
(iv) Suppose X1 and X2 are normally distributed, determine the percentage of all pairs of independent samples of sizes n1 = 3 and n2 = 6 with the property that the difference between the sample means, x bar1 - x bar2, is between -9 and 11.
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