The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day They would like the estimate to have a maximum error of 0 13 gallons A previous study found that for an average family the standard deviation is 1 3 gallons and the mean is 15 2 gallons per day If they are using a 85 level of confidence how large of a sample is required to estimate the mean usage of water Round your answer up to the next integer Answer How to enter your answer opens in new window Keypad Keyboard Shortcuts Tables