A Firm has two photocopying machines. The old one is available for use 80% of the time and the new one is available for use 91% of the time.
The machine availabilities are independent of each other.
a) Construct a tree diagram to display the information above.
b) Determine the probability that at a randomly selected time:
i) Both machines are available.
ii) neither is available.
iii) exactly one is available.
iv) atleast one machine is available.