SOLUTION: A department store analyzed its most recent sales and determined the relationship between the way a customer paid for an item and the price category of the item. the joint probabi

Under $20       	cash 0.09 	credit 0.03 		debit card 0.04
$20-100 dollars 	Cash 0.05 	credit 0.21 		debit card 0.17
Over $100  		cash 0.01 	credit card 0.26 	debit card 0.14

find the probability that an item is purchased for over $100 given that it was paid by a credit

This problem is on  " conditional probability ".



The words "given that it was paid by a credit"  tell you that you can restrict/reduce your selection/(your attention)

by considering credit card shopping, ONLY.



Then you see  from the Table  that  0.03 + 0.21 + 0.26 = 0.50  of all items  are payed by credit cards;

OF THEM,  the part which are over $100  is 0.26  (see the Table).



Therefore, the conditional probability under the problem's question is


    P =  = 0.52.      ANSWER