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# S2 - Sampling watch

1. Hey could anyone help me with this question:

Eggs sold in a supermarket are packed in boxes of 12. For each egg, the probability that it is cracked is 0.05, independently of all other eggs. A random sample of n boxes is selected and the variance of the sample mean number of cracked eggs in a box is 0.019. Find the value of n.

If you could go through each step in detail, would be great. Statistics does not seem to be one of my strengths.

Thanks!
2. stats isnt my best subject as well, i guess u use the equation variance/n= 0.019 but i do not how to solve the original variance for when only one box is chosen
3. Well it looks like binomial, so variance is np(1-p). So I think what it is, is n=12, p=0.05, variance is 0.57 for one box, then 0.57/0.019 = 30.
4. this is why i love the student room,
i find old posts which is exactly what im doing now

thank you

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Updated: December 10, 2013
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