The length of time between billing dates as well as checks received as well as deposited for non-delinquent accounts of oil company's monthly credit card customers is 13.5 days with the standard deviation of 3 days. A bank claims if the company employed a lockbox system, it could reduce the company's average time. Thirty-six (36) accounts were randomly chosen and tested using the lockbox system. The average time was found to be 13 days. Describe your conclusion at the 2.5% level of significance?