A computer manufacturer that sells notebook computers directly to customers has been having problems with one of its models-it seems that about 10% of the units are inoperable upon arrival to the customer. They are functional when tested at the factory, but there is some problem associated with the shipping/handling process that the company's engineers have not yet been able to identify and correct.
A highly valued customer places an emergency order for 8 of these notebooks, and wants them delivered overnight and ready for use in the field by tomorrow.
Wanting to be honest with this customer, and wishing to help ensure that the customer receives at least 8 working computers, the manufacturer offers to send 9 units instead of the 8 that the customer needs. The customer accepts this gesture of goodwill and 9 units are sent. What is the probability that the customer will end up with at least 8 working computers?