A firm is planning to introduce a new detergent in New York. JD Research Inc. (John and Dan) needs to estimate the mean weekly usage of laundry detergent per household. The laundry usage follows a normal distribution.

1. John decides to sample 25 households at random and observes mean usage of 4.5 oz. and a sample standard deviation of 1.5 oz. Give a 95% confidence interval for the mean usage of laundry detergent in the city (just write the formula with the appropriate numbers).
2. Meanwhile Dan goes to Brooklyn. The laundry usage follows a normal distribution. Dan wants to estimate the mean weekly usage of laundry detergent per household to within 0.25 oz. with a confidence interval of 95%. How large a sample of households should be selected if it is known that 99% of the households in the city use between 1 and 10 oz.?