Question: 31 ATMs must be stocked with enough cash to satisfy customers making withdrawals over an entire weekend. But if too much cash is unnecessarily kept in the ATMs, the bank is forgoing the opportunity of investing the money and earning interest. Suppose that at a particular branch the expected (i.e. population) mean amount of money withdrawn from ATMs per customer transaction over the weekend is $160 with an expected (i.e. population) standard deviation of $30.

a) State the null and alternate hypothesis

b) If a random sample of 36 customers transactions is examined, and the sample mean withdrawal is $172, is there evidence to believe that the population average withdrawal is no longer $160 and why (use a 0.05 level of significance)

c) Compute the p-value and interpret its meaning.