Answer all please

When the population standard deviation is unknown we use to instead of zc. O True O False 12 of 50 All else being equal, the higher the confidence level O the wider the confidence interval O the narrower the confidence interval 13 of 50 interval? If you increase the sample size and confidence level at the same time, what will happen to the length of your confidence O make it bigger make it smaller it will stay the same O cannot be determined from the given information 14 of 50 In calculations of the confidence interval for a mean with known population o, Zc (SE) represents O the alpha level the confidence level the margin of error 15 of 50 In constructing a confidence interval, x is used as an estimate of the population mean. True O False 16 of 50 In calculations of the confidence interval for a mean with known population o, Zo represents the alpha level the confidence level the margin of error