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3. A simple random sample of 100 households located in a city recorded the number of people living in the household, X. It is known that there are 10,000 households in the city. In the sample 100 100 EX: =320, EX? = 1250. i=1 (a) Find a 95% confidence interval for the population mean using the normal ap- proximation of / distribution. (b) In the same survey, 70% of the (sampled) households have cable tv. Find a 95% confidence interval for the proportion of households having cable tv