A wafer fab has 6 deposition machines. The probability of a machine is not working and being "off-line" is 5%. Answer the following questions relating to the foundry. The machine is either working or not working. Machines are independent with respect to operation and failure. The probability of failure is the same for all machines. (Answer to 4 decimals.)

What probability distribution would you use to solve? (Binomial, Poisson, Normal or Exponential) (B, P, N or E for your answer)

Find the probability that exactly 2 machines will not be working.

Find the probability that exactly 4 machines will be working. Find the probability that three or more machines will be down.

For planning purposes how many of these machines should you plan on for your capacity calculation; that is, what is the expected number of machines working?

What is the probability that at least one machine is not working?