An investigator hypothesizes that cholesterol levels in chil

An investigator hypothesizes that cholesterol levels in children might be affected by educating their parents on proper nutrition and exercise. A sample of 40 families with a child between the ages of 10 to 15 who has been diagnosed with high cholesterol agree to participate in the study. All parents are provided educational information on nutrition and exercise. After following the prescribed program, their child\'s total cholesterol level is measured. The children\'s mean cholesterol is 175 with a standard deviation of 19.5. Is there significant evidence of a reduction in total cholesterol in the children? Run the appropriate test at the 5% level of significance and assume that the null value for total cholesterol is 191.

Solution

Its not clear in the question if the childern\' standard dviation refers to the sample or not. I will assume that it does refer to the sample deviation. Otherwise, the standard dev would have benn 19.5/sqrt(40)

Let the null hypothesis be that \" There is no change in cholesrtol level even after educating parents\". The alternate is going to be mutually exlusive of this. - there is change in cholestrol level even after educating parents.

The sample size is 40

Mean of sample is 175

Sample\' STDEV is 19.5

Mean of pop. ia 191

So, Z = (175-191)/ (19.5) = -.82, which yeilds 0.2061 which is >.025. So, we cant reject null hypothesis. Resulting in the conclusion that \"Cholestrol level aren\'t effected upon educating parents\"

Please note that we complare the .2061 with ,025 and not ,05 as its a 2 tailed test.