# 5-sigma anomaly problem

Struggling with how to start this question:

A factory processes chickens with masses between 1.5 and 2.5kg. "Natural" chickens have masses equally spread across this range. However, "GM" chickens have masses between 2.3 and 2.4kg.

If a factory produces 10 million chickens per year, how many GM chickens would be required to produce a 5-sigma anomaly in the chicken mass spectrum?

I understand that the chicken masses are going to follow a normal distribution but quite lost after that. Anybody want to shed some light?

• If values are equally spread across a range, they are not normally distributed. That sounds like a uniform distribution. – Peter Flom Dec 7 '13 at 14:32
• Shot in the dark, but you don't happen to be an Edinburgh Uni student do you? Physics Skills? I have calculated a value for the standard deviation, but am not sure if for the 5 sigma anomaly, the want the average chicken mass to surpass 5*sigma. I also think that the GM chickens may be normally distributed, but the normal chickens are uniform with each chicken 1/(10*10^6) kg heavier that the last, from 2.5kg – user35882 Dec 8 '13 at 22:25
• Can you include the definition of "5-sigma anomaly" that applies? – Glen_b Dec 8 '13 at 23:20