SOLUTION: Amniocentesis tests result in miscarriage 0.5% of the time. Assuming each test is independent and follows a Bernoulli random variable, then what is the variance of one test? What i

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Question 258784: Amniocentesis tests result in miscarriage 0.5% of the time. Assuming each test is independent and follows a Bernoulli random variable, then what is the variance of one test? What is the variance of 400 tests? I found the equation for variance p(1-p), but it doesn't take into account the number of tests.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Amniocentesis tests result in miscarriage 0.5% of the time. Assuming each test is independent and follows a Bernoulli random variable, then what is the variance of one test? What is the variance of 400 tests? I found the equation for variance p(1-p), but it doesn't take into account the number of tests.
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For a binomial distribution variance = npq
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Your problem:
variance = 400*0.05*0.95 = 19
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Cheers,
Stan H.