Geometry math question no guessing and show work you

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.

Acircle has a radius of 5/6 units and is centered at (3.6, 7.8) write the equation of this circle

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)