The daily number of computer stoppages was observed over 6months at a computer c

Question

The daily number of computer stoppages was observed over 6months at a computer centre. the frequency distribution is asfollows; Number of stoppages Frequecy 0 101 1 52 2 13 3 10 4 4 Total 180 a) Estimate the mean b)Estimate the variance c)does the number of computer stoppages occurrandomly in a way that obeys conditions for a Poissondistribution? The daily number of computer stoppages was observed over 6months at a computer centre. the frequency distribution is asfollows; Number of stoppages Frequecy 0 101 1 52 2 13 3 10 4 4 Total 180 a) Estimate the mean b)Estimate the variance c)does the number of computer stoppages occurrandomly in a way that obeys conditions for a Poissondistribution? Number of stoppages Frequecy 0 101 1 52 2 13 3 10 4 4 Total 180

Explanation / Answer

a) Mean = (0*101 + 1*52+2*13+3*10+4*4)/180 = 0.69 b) variance = E[(X-mean)^2] =(52*(1-0.69)^2+13*(2-0.69)^2+10*(3-0.69)^2+4*(4-0.69))/180                                              = (52*0.0961 + 13*1.7161+10*5.3361+4*10.9561)/180                                              = 124.49/180 = 0.692 c) since the mean and variance are equal, then yes (property ofPoisson distribution:http://en.wikipedia.org/wiki/Poisson_distribution )

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