A computer store has 75 printers of which 25 are laser printers and 50 are ink jet printers. if a group of 10 printers is chosen at random from the store, find the mean and variance of the number of ink jet printers.

A computer store has 75 printers of which 25 are laser printers and 50 are ink jet printers. if a group of 10 printers is chosen at random from the store, find the mean and variance of the number of ink jet printers.
The mean of the number of ink jet printers will be:
mean=np
n=10
p=50/75
mean=10*50/75
mean=6 2/3

Variance:
variance=npq
=6 2/3*25/75
=2 2/9