Please answer this correctly

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

Renting a room at the willow tree resort costs $125 for 2 people. each additional person is $25. write an expression that shows the cost for n extra people

What is the correct answer? urgent you