4. An environmental group conducts a study of the water use within a city of 24,000 people. With the cooperation of the local water company, they take a simple random sample of 900 residential addresses receiving water service. Among these 900 addresses, the average water use is 5,500 gallons per month, with a standard deviation of 3,000 gallons. (a) TRUE or FALSE (circle one): The histogram of water use at the sampled addresses approximately follows the normal curve. Explain your answer. (b) TRUE or FALSE (circle one): It is appropriate to use the normal approximation to nd a 95%-condence interval for the average water use among all residential addresses receiving water service. Explain your answer. (c) What additional data would you need to construct a 95%condence interval for the average residential water use per person in the city? 5. A simple random sample of 1,000 people is taken to estimate the percentage of Democrats in a large population. It turns out that 543 of the people in the sample are Democrats. The sample percentage is (543/1000) x 100% = 54.3%. The SE for the sample percentage of Democrats is 1.6%. (You don't need to check this calculation.) (a) TRUE or FALSE (circle one): (51.1 %, 57.5%) is a 95%-condence interval for the percentage of Democrats in the population. Explain your answer. (b) TRUE or FALSE (circle one): (51.1%, 57.5%) is a 95%-condence interval for the percentage of Democrats in the sample. Explain your answer. (c) TRUE or FALSE(circle one): There are about two chances in three for the percentage of Democrats in the population to be in the range (52.7%, 55.9%). Explain your