Simplify the expression. Explain each step 7(4y)

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.

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.

Tell whether the two rates form a proportion