A machine on average produces 4 defective items out of a batch of 100 items.

Find the probability that a batch of 50 items has 3 defective items in it using the Poisson probability distribution.

the problem is..

i just want to know the mean or average value for batch of 50 items..

i got mean = 2

because for 100 items, the mean is 4..

............for 50 items, the mean would be 2..

correct?