Question

Use the given degree of confidence and sample data to construct a confidence interval for the population mean μ. Assume that the population has a normal distribution. A laboratory tested twelve chicken eggs and found that the mean amount of cholesterol was 185 milligrams with s = 17.6 milligrams.

Required:
Construct a 95% confidence interval for the true mean cholesterol content of all such eggs.

Answer 1

CI ≈ (173.8 < μ < 196.2)

Explanation:

We are told that laboratory tested twelve chicken eggs. Thus;

n = 12

Mean; x¯ = 185 mg

S.D; s = 17.6 mg

DF = n - 1 = 12 - 1 = 11

We have a 95% confidence level. Thus; α = 0.05

Since n < 30, we will use t-sample test.

Thus, from t-table attached at 95% Confidence level and DF = 11, we have;

t = 2.201

Thus,formula for Confidence interval is;

CI = (x¯ - t(s/√n)) < μ < (x¯ + t(s/√n))

CI = (185 - 2.201(17.6/√12)) < μ < (185 + 2.201(17.6/√12))

CI = (185 - 11.1825) < μ < (185 + 11.1825)

CI = (173.8175 < μ < 196.1825)

CI ≈ (173.8 < μ < 196.2)