Question

What is the general way of finding the confidence interval when sigma is known?

A) 90 percent
B) 95 percent
C) 99 percent
D) None of the above

Answer 1

To find the confidence interval when the population standard deviation (sigma) is known, use the formula CI = sample mean ± (Z * (sigma/ √n)).

Step-by-step explanation:

To find the confidence interval when the population standard deviation (sigma) is known, the general formula is:

CI = sample mean ± (Z * (sigma/ √n))

Where CI is the confidence interval, Z is the Z-score corresponding to the desired confidence level, sigma is the population standard deviation, and n is the sample size.

For example, if sigma is known and we want a 95 percent confidence interval, the Z-score for a 95 percent confidence level is approximately 1.96. So the formula becomes:

CI = sample mean ± (1.96 * (sigma/ √n))