Question

What is the 95% CI for data set 2?

Answer 1

Answer: 20 ± 11.32

Explanation: Confidence Interval (CI) is an interval of values where there is a % certainty the true mean value lies in. For example, a 95% CI means there is a 95% certainty the true mean value lies in the interval.

For the data set 2, z-value for 95% confidence interval is z = 1.96

Formula to calculate CI is

x ± $z\frac{s}{\sqrt{n} }$

where

x is mean

z is z-value

s is standard deviation

n is the sample number

Then:

20 ± $1.96\frac{10}{\sqrt{3} }$

20 ± $1.96\frac{10}{1.7320}$

20 ± $\frac{19.6}{1.7320}$

20 ± 11.32

The 95% CI is 20 ± 11.32, which means there is a 95% certainty the true value is between 8.68 and 31.32.