I don’t get how to solve it

Question

If n=400 and  (p-hat) = 0.9, construct a 95% Confidence Interval.In order to use technology, you need to compute the number of successes:x = n*

Give your answers to three decimals.

Answer 1

If you're using technology, such as a TI-84, there is a confidence interval function for this type of problem, It is called 1-PropZInt. It is found if you push the STAT button and then arrow over until you see the TESTS menu. It is down by choice A. We are given n and the confidence level (0.95). According to the instructions in the question, to get x, multiply n and p-hat. 400 * 0.9 = 360. Enter all these values in, and select CALCULATE. The confidence interval is between 0.708 and 0.792.