Which of the following is the width of the confidence interval for the population mean?

The width of a confidence interval for a population mean is calculated by subtracting the lower limit of the interval from the upper limit. However, it can also be calculated directly from the standard error and the z-score or t-score associated with the desired level of confidence. Here are the steps:

1. Calculate the Standard Error: The standard error (SE) is a measure of the variability in your sample mean. It is calculated as the standard deviation (SD) divided by the square root of the sample size (n). The formula is SE = SD/√n.

2. Find the Z-score or T-score: The z-score or t-score corresponds to the desired level of confidence. For example, a 95% confidence level corresponds to a z-score of 1.96 in a normal distribution. If the population standard deviation is unknown, a t-score from the t-distribution is used instead, and the exact value depends on the sample size and desired confidence level.

3. Calculate the Margin of Error: The margin of error (E) is calculated as the product of the standard error and the z-score or t-score. The formula is E = SE * Z or E = SE * T.

4. Determine the Width of the Confidence Interval: The width of the confidence interval is twice the margin of error. The formula is Width = 2 * E.

So, the width of the confidence interval for the population mean is twice the product of the standard error and the z-score or t-score.