posted by steven .
we developed a 95% z confidence interval for the mean BMI of women aged 20 to 29 years, based on a national random sample of 654 such women. we assumed there that the population standard deviation was known to be 7.5. in fact the sample data had mean BMI of 26.8 and standard deviation s=7.42. what is the 95%t confidence intervalfor the mean BMI of all young women?
CI95 = mean + or - 1.96(sd divided by √n)
...where + or - 1.96 represents the 95% confidence interval using a z-table, sd = standard deviation, √ = square root, and n = sample size.
Substitute the values into the formula and calculate the interval.