Data analysis

Question

a researcher has a data set of homicides occurring in large southern metropolitan areas consisting of 304 cases with a mean of 25.68 and a standard deviation of 11.26, the researcher has established a=.05, calculate the resulting confidence Interval for this set of data and interpret the confidence interval in words 

Answer 1

The 95% confidence interval is (24.28, 26.92) words.

How to find this :

With n=304 cases (large sample), mean=25.6, and standard deviation=11.7, use the z-interval formula since population SD is given.

First, standard error = 11.7 divided by square root of 304, which is about 0.67.

For 95% confidence, multiply by 1.96 to get margin of error ≈1.32

Subtract and add to mean: 25.6 - 1.32 = 24.28; 25.6 + 1.32 = 26.92.