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Grades 11-12 Video Solutions 2011
11&12 Video Solutions 2011 problem10
11&12 Video Solutions 2011 problem10
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Video Transcription
Question number 10. Two brothers, Gervase and Protase, answered truthfully a question regarding the number of members on the debate team, which they are both part. Gervase said, all the team members except five are women. Protase said, among any six randomly chosen members of our team, there are always at least four women. How many members belong to the debate team? What we have so far is that the two brothers are on the team, so there are at least two men and out of all the team members, all except five are men, so that means five, exactly five are women. And so this tells us that we have at least seven members. Then looking at the second statement, out of any six randomly chosen members, always four are women, so always four of six are women. And if we try to increase the number of the members on the team past seven, we can add either a man or a woman. So adding a woman is not allowed because then we would increase the number of women past five and that is breaking the first statement. And if we add one more man, then we could choose three men and three women and violate the second statement. So adding a woman violates the first statement and adding a man violates the second statement, both of which are true, therefore we conclude that there are at most seven members. And together, combining this information, we see that there are exactly seven, so the answer is B.
Video Summary
The debate team has exactly seven members. Gervase stated that all members but five are women, indicating five women are on the team. Protase mentioned that in any group of six randomly chosen members, there are at least four women, confirming the team's composition. Since both statements allow for exactly seven members, with two men and five women, adding additional members would violate one of their statements. Therefore, the team consists of seven people.
Keywords
debate team
seven members
women
men
composition
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