Private colleges and universities rely on money contributed by individual and corporations for their operating expenses. Much of this money is put into a fund called an endowment , and the college...

Private colleges and universities rely on money contributed by individual and corporations for their operating expenses.  Much of this money is put into a fund called anendowment, and the college spends only interest earned by the fund.  A recent survey of seven private colleges in the US revealed the following endowments (in millions of $):

Note that the sample mean is 155.  What value will be used as the point estimate for the standard deviation of endowments of all private colleges in the US?  (note that we uses to estimate σ)                             ["", "", "", ""]

The t value to use in a 90% confidence interval is                             ["", "", "", ""]

A 90% CI for the mean endowment of all private colleges in the US is 155 + _____                            ["", "", "", ""]