17. The owner of an appliance store is interested in the relationship between the price at which an item is sold (retail price or sale price) and the customer's decision on whether or not to purchase an extended warranty for the item. The owner has constructed the accompanying joint frequency table, based on a study of 2,000 sales invoices. Suppose that one sales invoice is selected at random from the 2,000 studied invoices. The relevant events are de fined below. R: the item was purchased at the retail price W: an extended warranty was purchased for the item Extended warranty Price Purchased (V Not pure ha sed (w ] Re tall price (R 420 11 40 Sale price ( R ) 280 1 80 (a) 0 Obtain a table of probabilities for all joint events. Obtain marginal probabilities for the table in (a) 0. (b) Using the table of joint probabilities, obtain the following probabilities: O the probability that the selected invoice is for an item purchased at the retail price