A study showed that 60% of The Wall Street Journal subcribers watch CNBC every day. Of these, 70% watch it outside the home. Only 20% of those who don't watch CNBC every day watch it outside the home. Let D be the event "watches CNBC daily" and O be the event "watches CNBC outside the home."
a) Sketch a tree based on this data.
b) Calculate the probability of all joint probabilities
c) Verify that the joint probabilities sum to 1