A sample of 65 night-school students' ages is obtained in order to estimate the mean age of night-school students. x bar = 25.2 years. The population variance is 28.

Question

(a) Give a point estimate for ì. (Give your answer correct to one decimal place.)
Correct: Your answer is correct. .

(b) Find the 95% confidence interval for ì. (Give your answer correct to two decimal places.)
Lower Limit Incorrect: Your answer is incorrect. .
Upper Limit

(c) Find the 99% confidence interval for ì. (Give your answer correct to two decimal places.)
Lower Limit
Upper Limit

Answer 1

a. 25.2 years

b. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability
(±.025) and its Z score.

95% = mean ± Z SEm

SEm = SD/√n

SD = √variance

c. Same process with ±.005.