There is growing concern that Americans are generating too much trash. More zoning permits are being sought for landfills in rural areas, and trash haulers move garbage out of state and even out to...

There is growing concern that Americans are generating too much trash. More zoning permits are being sought for landfills in rural areas, and trash haulers move garbage out of state and even out to the ocean. In a recent study, 65 households were randomly selected, and the amount of trash (in pounds) generated by each in one week was recorded. The sample mean was x 5 52.3 with a standard deviation of s 5 10.75. Assume normality.

a. Find a 98% confidence interval for the true mean amount of trash generated by an American household per week.

b. Find an approximate 98% confidence interval for the true mean amount of trash generated by an American household per week (based on a Z distribution rather than a t distribution). Compare your answers in parts (a) and (b). How do they differ?

 c. Find a 95% confidence interval for the variance in the amount of trash generated by an American household per week.