Please solve this! Need it to finish my class. Giving Brainliest to whoever gets it right!

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.

Find three consecutive numbers such that the sum of one-fourth the first and one-fifth the second is five less than one-seventh the third

How many triangles can be drawn with side lengths 4 centimeters, 4.5 centimeters, and 9 centimeters? explain