Question 18
Anh has 10 balls in a bag, in three colors: red, blue and yellow. Anh and Bình take turns drawing some balls and putting them back, with these results:
Anh draws 6 times and gets 5 red balls and 1 blue ball;
Bình draws 5 times and gets 3 red balls and 2 blue balls.
Finally, Châu draws 5 balls and keeps them (does not put them back). What is the greatest number of yellow balls Châu could draw, given that all three colors remain in the bag?
**Assumption for the answer:** During Anh’s turn and Bình’s turn, each ball is drawn without replacement. Only after the whole group of 6 or 5 balls has been drawn is that group returned to the bag. Use this assumption to answer.
Anh draws 6 times and gets 5 red balls and 1 blue ball;
Bình draws 5 times and gets 3 red balls and 2 blue balls.
Finally, Châu draws 5 balls and keeps them (does not put them back). What is the greatest number of yellow balls Châu could draw, given that all three colors remain in the bag?
**Assumption for the answer:** During Anh’s turn and Bình’s turn, each ball is drawn without replacement. Only after the whole group of 6 or 5 balls has been drawn is that group returned to the bag. Use this assumption to answer.