(9). The weekly mean amount of household trash was reported to be 45 lbs. There is a growing concern that people is generating much trash currently. A random sample of 9 households were selected. The sample mean is 48 lbs. Assume the current weekly amount of household trash is normal with standard deviation 0' = 5 lbs. 1(4). Find the minimum sample size n such that the width of two-sided 99% confidence interval of the current weekly mean amount of household trash is 2.5