statistics
posted by autumn .
A company manufactures caclculators in batchers of 64 and there is a 5% rate of defects. Find the probability of getting exactly three defects in a batch

I think I remember a bit of this from when we were generating OC curves for a math modeling project last semester.
In my notes there is the equation:
P(d)= (n!/(d!(nd)!))*(p^d)(1p)^(nd)
It's assumed that the total lot is very large, so when you take n, the sample size, out doesn't change the remainder.
P(d)= prop of observing exactly d
number of defectives= d
random sample= n
p= fraction of defectives per lot.
Hope this helps