Please help!! "Sarah drove 40 miles per hour. In 3 hours, Sarah drove 120 miles. Which is a valid proportion to represent this description?"

Arandom sample of 45 observations results in a sample mean of 68. the population standard deviation is known to be 23 a. compute the margin of error at a 959% confidence interval. b. compute the 95% confidence interval for the population mean c. compute the 90% confidence interval for the population mean. d. compute the 75% confidence interval for the population mean