1. The problem statement, all variables and given/known data
Suppose that 1% of cars have defective brake lights and n cars are to be inspected. How large should n be for the sample to have a probability of at least 50% of containing a car with a defective brake light? Give an answer using a Poisson approximation with an appropriate mean.
3. The attempt at a solution
Let X-Bin(n, 0.01).
We can approximate X with the Poisson distribution assuming n large and with mean 0.01n.
That is, X≈Po(0.01n).
We want P(X=1)≥ 0.5 which yields ne^-0.01n ≥ 50.
Then I'm stuck. Is this correct so far and any direction on where to go from here will be appreciated. Thanks.
Suppose that 1% of cars have defective brake lights and n cars are to be inspected. How large should n be for the sample to have a probability of at least 50% of containing a car with a defective brake light? Give an answer using a Poisson approximation with an appropriate mean.
3. The attempt at a solution
Let X-Bin(n, 0.01).
We can approximate X with the Poisson distribution assuming n large and with mean 0.01n.
That is, X≈Po(0.01n).
We want P(X=1)≥ 0.5 which yields ne^-0.01n ≥ 50.
Then I'm stuck. Is this correct so far and any direction on where to go from here will be appreciated. Thanks.
via Physics Forums RSS Feed http://www.physicsforums.com/showthread.php?t=719619&goto=newpost
0 commentaires:
Enregistrer un commentaire