the reduction in cholesterol level after eating a certain brand of oatmeal for b
ID: 3174091 • Letter: T
Question
the reduction in cholesterol level after eating a certain brand of oatmeal for breakfast for one month in people with cholesterol levels over 200 is normally distributed, with mean (in milligrams) u and standard deviation sigma=8. Although the brand advertises that eating their oatmeal for breakfast daily for one month will produce a mean decrease in cholesterol of more than 20 points for people with cholesterol levels over 200, you believe that the mean decrease in chlesterol is acutally less than advertised. To explore this ,you test the hypothesis Ho: u=20 Ha: u < 20 at the 0.05 level. You will do this by randomly selecting 144 people with cholesterol levels over 200 and, after eating this brand of oatmeal for one month, computing the mean decrease xbar in cholesterol levels of the subjects. If you observe a sample mean cholesterol reduction of xbar= 18.52, the p value obtained is:
between 0.01 and 0.025
less than 0.01
between 0.025 and 0.5
between 0.05 and 0.10
Explanation / Answer
It is one-tailed test.
z = (x bar - µ/(s/Ön)
= (18.52-20)/(8/Ö144)
= -2.22
P-value = P (z<-2.22)
By using normal distribution table we get,
P (z<-2.22) = 0.0132
Answer:
Between 0.01 and 0.025
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