Determine a value of x for each of the following. Give answers in simplest exact form. cos (11pi/31) = sinx

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.

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2

First to answer will be the brainliest i need the answer asap