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| Question 1183718:  Of grocery shoppers who have a shopping cart, 70 percent pay by credit/debit card (event C1), 20 percent pay cash (event C2), and 10 percent pay by check (event C3). Of shoppers without a grocery cart, 50 percent pay by credit/debit card (event C1), 40 percent pay cash ((event C2), and 10 percent pay by check (event C3). On Saturday morning, 80 percent of the shoppers take a shopping cart (event S1) and 20 percent do not (event S2).
 a)	Construct a contingency table base on the statement above.
 b)	Sketch a tree diagram based on these data.
 c)	Calculate the probability of all joint probabilities
 Answer by robertb(5830)
      (Show Source): 
You can put this solution on YOUR website! I will do only part (c).  (You should be able to do part (b) from the way I wrote the probabilities below.) 
 P(with shopping cart ∩ card)  = 0.56
 P(with shopping cart ∩ cash)  = 0.16
 P(with shopping cart ∩ check) = 0.08
 
 P(without shopping cart ∩ card)  = 0.10
 P(without shopping cart ∩ cash)  = 0.08
 P(without shopping cart ∩ check) = 0.02
 
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