statistics
posted by john on .
Can someone provide me with some assistance in answering this question..
A company manufacturers batteries in BATCHES of 18 and there is a 3% rate of defect. Find the standard deviation for the number of defects per batch.
The probability of a defect is p = 0.03
The mean number of defects in a batch of N = 18 is m = p N = 0.03 x 18 = 0.54
The standard deviation of the number of defects in a batch of 18 is
sigma = sqrt [N p (1p)] = 0.72, which actually exceeds the mean value in this case.

Can you explain how you got the standard deviation of the number of defects in a batch of 18 is sigma=sqrt[N p (1p)]=0.72. IN OTHER WORDS HOW DID YOU GET 0.72