Thread: Variance Help

The probability of a manufactured article being in perfect condition is 0.84. The articles are packed in batches of n articles.
Given that the variance of the number of perfect articles in each batch is 6.72, find the value of n.

Well i dont seem to get it how to do it, if someone could help would be very appreciated.
Thank you in anticipation.

Hello,

This problem deals with a binomial distribution...

we have its expectation equal to np, and its variance equal to np(1-p)
you have a system of two equations with two unknowns (p and n).
solve for n

Thank you now i got it