9.38) Find the large sample confidence interval for the population standard deviation where

(a) s = 10.89, n = 60, and the confidence interval for the population standard deviation is 95%;

(b) s = 1.29, n = 100, and the confidence interval for the population standard deviation is 98%

(c) s = 2.95, n = 200, and the confidence interval for the population standard deviation is 99%

9.50) In a sample survey of 2,500 commuters, 900 said that they regularly use public transportation. Conduct a 95% confidence interval for the corresponding true proportion of commuters who regularly use public transportation.

9.56) A large personal computer manufacturer wants to determine from a sample what proportion of households intend to purchase personal computer within the next 12 months. How large a sample will the manufacturer need to be able to assert with a probability of at least 0.95 that the sample proportion will not differ from the true proportion by more than 0.05?