Question

Activated protein-C (APC) resistance is a serum marker that has been associated with thrombosis (the formation of blood clots often leading to heart attacks) among adults. APC values for 5 randomly chosen individuals at high-risk for heart attack are listed below. 2.2, 3.4, 2.7, 3.3, 3.0 Note: The sample standard deviation is s = 0.49 Calculate a 95% confidence interval for the mean APC level of individuals from this population

Answer 1

Solution:

Confidence interval for Population mean is given as below:

Confidence interval = Xbar ± t*S/sqrt(n)

From given data, we have

Xbar = 2.92

S = 0.49

n = 5

df = n – 1 = 4

Confidence level = 95%

Critical t value = 2.7764

(by using t-table)

Confidence interval = Xbar ± t*S/sqrt(n)

Confidence interval = 2.92 ± 2.7764*0.49/sqrt(5)

Confidence interval = 2.92 ± 0.6084

Lower limit = 2.92 - 0.6084 = 2.31

Upper limit = 2.92 + 0.6084 = 3.53

Confidence interval = (2.31, 3.53)