Question 320860
A doctor believes that the standard deviation of systolic blood pressure is 450.
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A random sample of 24 patients found a standard deviation of 520. 
Assume the variable is normally distributed and a=0.01. 
What is the critical value? 

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The problem statement implies you will do an F-test.
You need to look at an F-distribution Table and find 
the F value with a right tail of 1% with the proper
degrees of freedom.
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F= larger variance/smaller variance = 520/450
df for numerator: 23
df for denominator: infinity
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Ans: F-value for right-tail of 1% = 1.6402
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Cheers,
Stan H.