thanks in advance

Show your work. 1. Suppose a population that has mean 90 and standard deviation 20. How many observations, n, should there so that the standard deviation of the sampling distribution of a? is 1? 2. According to the CDC, the average height of American men 20 yea rs old and up is 69 inches. Assume the distribution of height is Normally distributed with a standard deviation of 3 inches. a. What is the probability of randomly selecting a man taller than 72 inches? b. What is the probability of randomly selecting three men with a sample mean height greater than 72 inches? c. What is the probability of randomly selecting three men all with heights greater than 72 inches