A mining company needs to estimate the average amount of copper ore per ton mined. A random sample of 50 tons gives a sample mean of 146.75 pounds. The population standard deviation is assumed to be 35.2 pounds. Give a 95% confidence interval for the average amount of copper in the "population" of tons mined. Also give a 90% confidence interval and a 99% confidence interval for the average amount of copper per ton.