10/3=? /9 and how do you get the answer

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 the roots of the polynomial function f(x) = x^3 + 2x^2 + x

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.