A student looked up the number of years served by 35 of the more than 100 supreme court justices. the average number of years served by those 35 justices was 13.8. if the standard deviation of the entire population is 7.3 years, find the 95% confidence interval for the average number of years served by all supreme court justices.

Finding confidence interval:1. Determine the confidence level and its corresponding z value. 95% = 1.96

2. Find the sample mean and the standard deviation. 13.8 is the mean and 7.3 is the standard deviation. And also n = 35.

3. Then multiply the z value, then divide this to sqrt of n. This is called the margin of error.± 1.96 (7.3 / sqrt (35) = ± 1.96 (1.1229) = 2.2009

Add that number then subtract to the mean. Confidence interval: 11.5991 < x < 16.0009