Ex 7.11 only C)would the interval be longer or shorter than the 99% confidence interval? Longer or shorter that the 90% confidence interval?

the new oil has a higher mean dielect 7.9 Noise level tests were done on 40 new light rail vehicles (LRVs-the new name for trolley cars) The results of the test gave a sample mean of 65 decibels and a sample standard deviation off decibels. (a) Find a 90% confidence interval for the mean decibel level Mu for this type of transit vehicle (b) What is the maximum error of the estimate at the 90% level? (c) Based on your answer in part (a), would you conclude that the new LRVs are quieter on the average than older-type trolley cars that had a mean decibel level of 80? .10 A union official wanted to estimate the mean hourly wage Mu of its members. A random sample of 100 members gave x = $18.30 and s = $3.25 per hour. (a) Find an 80% confidence interval for M. (b) Find a 95% confidence interval for u. (c) If you were to construct a 90% confidence interval for u (do not construct it), would the interval be longer or shorter than the 80% confidence interval? Longer or shorter than the 95% confidence interval? A transit official wanted to estimate the mean time yu for a bus trip between two cities. A random sample of 50 such trips gave x = 150 minutes and s = 15 minutes. (a) Find a 90% confidence interval for u. (b) Find a 99% confidence interval for M. (c) If you were to construct a 95% confidence interval for u (do not construct it), would the