A bank manager wanted to determine the mean number of transactions businesses make per month. For the sample of 55 businesses, he found that mean number of transaction per month to be 32 and standard deviation to be 7.5 transactions.
(a) Determine a 90% confidence interval for the mean number of business transactions per month. Show your calculations and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write down a sentence that clarifies it.