Use the confidence interval formula below, and the correct formula for means, to calculate the 95% confidence interval for any population mean of your choice. Tell what quantitative variable you chose. Then, write down (invent) the sample size (be sure it is 30 or above), the sample mean, and the sample standard deviation. Then, calculate the confidence interval. Remember, you are inventing all the values, so no two posts should look the same. (sample statistic E) < population parameter < (sample statistic + E) To calculate a confidence interval, the margin of error (E) must first be calculated. The margin of error, E, for means is: E=1.96sn where s is the sample standard deviation and n is the sample size. The margin of error, E, for a 95% confidence interval for proportions is: E=1.96pË(1pË)n¾¾¾¾¾¾ where pË is the sample proportion and n is the sample size.