A researcher wants to estimate the mean cholesterol level of people in his city.A random sample of 21 people yields a mean cholesterol level of 224 and a standard deviation of 12.Construct a 95% confidence interval.

A) (218.54,229.46)
B) (214.97,233.03)
C) (219.69,228.31)
D) (219.60,228.40)
E) (223.01,224.99)

Question

shaista shaikh · Accepted Answer

Final Answer : A, Explanation :  The 95% confidence interval for the mean is calculated using the formula: mean ± (t-value * standard deviation / sqrt(n)). With n = 21, the degrees of freedom is 20. For a 95% confidence level, the t-value from the t-distribution table is approximately 2.086. The calculation is 224 ± (2.086 * 12 / sqrt(21)), which gives the interval (218.54, 229.46).

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