The customer service department at Orange Bank has a service commitment that no caller shall wait longer than 30 seconds to be connected to an agent. The newly appointed customer service manager would like to find out if the bank meets this service standard she takes a random sample of 150 calls and finds that 36 of them had service standards she takes a random sample of 150 calls and finds that 36 of them had a wait time longer than 30 seconds

a)construct a 90% confidence interval estimate of the true proportion of calls with a wait time of more than 30 seconds. Margin of Error(percentage 2 decimals):?

90% confidence interval (2decimals) lower bound: upper bound

b)the manager wants to estimate the proportion of calls that are from overseas. she wants the estimate to be within 5% of the true proportion at 95% confidence level. how many calls need to be sampled