Probability I: Introductory Ideas

An employee at Info tech enter product information into the computer. The employee may use a light pen that transmits the information to the PC along with keyboard to issue commands, or fill out a bubble sheet and feed it directly into the old mainframe. Historically, we know the following probabilities

P(light pen will fail) = 0.025
P(PC keyboard will fail) = 0.15
P(Light pen and PC keyboard will fail) = 0.005
P(Mainframe will fail) = 0.25

Data can be entered into the PC only if both the light pen and keyboard are functioning.

1. What is the probability that the employee can use the PC to enter data?
2. What is the probability that either the PC fails or the mainframe fails? Assume they cannot both fail at the same time.

Solution