posted by Nancy on .
identify what is the 90 percent confidence interval for occupational prestige for respondents with only a bachelor's degree (N=750), given you have known their mean=52.74, standard deviation=12.67.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion of 5% in the smaller area. (90% leaves 5% in each direction.)
90% confidence interval = mean ± 1.645(SEm)
SEm = SD/√(n-1)
This gives confidence interval for means rather than individual scores.