A particular machine is  either  in  working  order  or  broken on any particular day. If it is in  working  order  on  some  day,  it  remains  so the next day with probability .7, while if it is broken on some day, it stays broken the next day with probability .2.
(a)      If it is in working order on Monday, what is the probability that it is in working order on Saturday?
(b)      If it is in working order on Monday, what is the probability that it remains in working order all the way through Saturday?