A local bank needs information concerning the savings account balances of its customers. A random sample of 15 accounts was checked. The mean balance was $686.75 with a standard deviation of $256.20. Find a 98% confidence interval for the true mean. Assume that the account balances are normally distributed. Round to the nearest cent. OA. ($326.21, $437.90) OB. ($487.31, $563.80) OC. ($238.23, $326.41) ($513 17 $860.33)