The square of a sum of six and a number

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.

The heaviest 16% of all men in weight weigh more than how many pounds ?

Write two subtraction equations that are equivalent to 5 + 12 = 17.