Stat - Confidence Intervals

Question

The Human Toxome Project (HTP) is working to understand the scope of industrial pollution in the human body. Industrial chemicals may enter the body through pollution or as ingredients in consumer products. In October 2008, the scientists at HTP tested cord blood samples for 20 newborn infants in the United States. In follow, represented that the targeted chemicals were found in each infant’s cord blood. 79, 145, 147, 160, 116, 100, 159, 151, 156, 126, 137, 83, 156, 94, 121, 144, 123, 114, 139, 99 Use this sample data to construct a 90% confidence interval for the mean number of targeted industrial chemicals to be found in an in infant’s blood

Answer 1

90% confidence interval

Alpha = 10% = 0.10

Alpha/2 = 0.05

Using TI-84 STAT editor, the data has a sample mean xbar = 127.45 and sample standard deviation s = 25.9645006

The confidence interval for mu is:

xbar ± z (sub alpha/2) * s/sqrt(n)

127.45 ± z sub 0.05 * s/sqrt(n)

127.45 ± 1.645 * 25.9645006/sqrt(20)

127.45 ± 9.55

(117.90, 137.00)