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If the mean of a binomial distribution is 12 and its standard deviation is 2, then the number of trials is : |
18 14 24 16 |
18 |
$X \sim B(n,p)$ Mean $=np=12$ Standard deviation $=\sqrt{npq}=2$ $npq=4$ Using $np=12$: $12q=4$ $q=\frac{1}{3}$ $p=1-q=\frac{2}{3}$ $np=12$ $n\cdot\frac{2}{3}=12$ $n=18$ The number of trials is $18$. |
