SOLUTION: a binomial distribution has a mean equal to 12 and a standard deviation equal to 2.683. Find n and p.

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Question 436745: a binomial distribution has a mean equal to 12 and a standard deviation equal to 2.683. Find n and p.
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
mu+=+np and sigma+=+sqrt%28npq%29
==> np = 12, and 2.683 = sqrt%28npq%29+=+sqrt%28np%281-p%29%29
==> 2.683+=+sqrt%2812%281-p%29%29
==> 7.198489 = 12(1-p)
==> 0.5999 = 1-p , to 4 decimal places.
==> .4001 = p, or p = 0.4 to the nearest tenth.
==> np = 12 ==> 0.4n = 12 ==> n = 30.