The mean sales per customer µ for all of the sales for your company last month is not known. Based on your past experience, you are willing to assume that the population standard deviation of sales, σ, is about $220. If you take a random sample of 100 sales, what is the value of the standard error of x¯¯?
If you take a random sample of 25 sales, what is the value of the standard error for x¯¯?
Remember that the sampling distribution of x¯¯ is normal with a mean of µ and a standard deviation of σx¯.