4. A radio station currently has a give-away contest under way. Once a contestant is selected, he or she is given two choices: (a) take $225 in cash or (b) randomly pick one of four envelopes (i.e., the probability of picking one is 0.25). The contents are $400, $300, $200, or $100 merchandise. (a) Draw the decision tree for this problem. (b) Find the expected monetary value (EMV) and decide which decision should be taken to achieve the highest EMV. (6 points)