Given the confidence interval (14.7,22.1). Find the margin of error 𝐸.

Answer 1

The confidence interval is the range between the sample mean minus E, and the sample mean plus E. Find the difference between the 2 numbers (22.1-14.7 = 7.4). Divide that number by 2, because that will tell you what was added to, and subtracted from, the mean. So we get 7.4/2 = 3.7 for the margin of error. If you needed to also find the sample mean, add 3.7 to the lower range number, 14.7, to get 18.4 for the mean.