Use the given degree of confidence and sample data to construct a confidence interval for the population mean u. Assume that the population has a normal distribution. A savings and loan association needs information concerning the checking account balances of its local customers. A random sample of 14 accounts was checked and yielded a mean balance of $664.14 and a standard deviation of $297.29. Find a 98% confidence interval for the true mean checking account balance for local customers. $455.65