In a survey, 55% of the voters support a particular referendum. If 40 voters are chosen at random, and X is the number of voters that support this referendum, find the mean and variance of X.

asked Apr 1, 2013 in Statistics Answers by anonymous

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1 Answer

mean=(number in the sample)*(probability) for a binomial distribution=40*0.55=22. This is an application of the binomial distribution µ=np where µ is the mean, n the sample size and p the probability. The variance is given by np(1-p)=40*0.55*0.45=9.9.
answered Jun 30, 2015 by Rod Top Rated User (486,780 points)
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