Please help me with these 3

1. For a normal distribution, assume the 'sample' standard deviation is 7. What is the maximal margin of error associated with a 95% confidence interval for the true population mean if n = 12. (Round to two decimal places) 2. A survey of 71 randomly selected students finds that they spend a mean of $442 per semester. Assume that the population standard deviation is $54 per month. Confidence Interval: What is the 9% confidence interval to estimate the population mean? Round your answers to two decimal places. 3. www.helpyourmath.com is an OER website to help students to save money on textbooks and homework systems. A survey of 31 randomly selected students finds that they save a mean of $200 per semester by using www.helpyourmath.com. Assume the date comes from a normal distribution and the sample standard deviation is $10 per month. Confidence Interval: What is the 9% confidence interval to estimate the population mean? Round your answers to two decimal places