3) Among the following statements about confidence interval estimation for one population mean with known population variance, which one is correct? For a given sample size, the interval length increases when the confidence level decreases. For a given confidence level, the interval length will decrease if the sample size decreases. If the interval length must be decreased for a given sample size, then the confidence level has to be decreased. To keep the interval length the same, the sample size must be decreased if the confidence level is increased