This is a simple substitution into a standard formula that should be in your textbook or class notes. The formula is here too: 1.3.5.2. Confidence Limits for the Mean.
Where exactly are you stuck?
What is the 2 sided confidence interval for the mean strength of a new structural column? The sample size is 25, the mean is 15,000 pounds, and the sample standard deviation is 200 lbs. Use a confidence level of 95 %.
This is a simple substitution into a standard formula that should be in your textbook or class notes. The formula is here too: 1.3.5.2. Confidence Limits for the Mean.
Where exactly are you stuck?