Suppose it is known that the average height of males in the population has a standard deviation of 8 inches while the standard deviation of height of females in the population has a standard deviation of 4 inches. Two random samples (one with men and another for women) are taken with the following results:

Male Sample???Female Sample

__????__

X = 72 inches?? X = 63 inches 

n = 100???n = 160

1. What is the value of the standard deviation of the difference in sample means?
2. Provide the lower bound and upper bound for a 95 percent confidence interval estimate for the difference in the average height of men and women in the population.
3. Provide the lower bound and upper bound for a 90 percent confidence interval estimate for the difference in the average height of men and women in the population.
4. Is there a significant difference in the average height of men and women given your results? Yes or no.
5. Defend your answer to Question 4 in one or two sentences.