Question: what is the formula for calculating confidence interval?
Answer: Confidence Interval for a Proportion Example 2: Steps Step 2: Look up the value you calculated in Step 1 in the z-table and find the corresponding z-value. The z-value that has an area of . 475 is 1.96. Step 3: Divide the number of events by the number of trials to get the “P-hat” value: 24/160 = 0.15.