posted by dell on .
a study found that the average time it took a person to find a new job was 130 days. If a sample of 36 job seekers was surveyed, find the 95% confidence interval of the mean. Assume the standard deviation of the sample is 12 days.
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.
Using your data:
CI95 = 130 + or - 1.96 (12/√36)
I'll let you finish the calculation to determine the interval.
I hope this will help.