Six people are seated around a circular table. There are at least two men and two women. There are at least three right-handed persons. Every woman has a left-handed person to her immediate right. None of the women are right-handed. The number of women at the table is
2
This problem requires us to determine the number of women seated at a circular table based on several conditions related to gender and handedness. Let's break down the information given:
From the conditions, we can establish crucial relationships:
We will now test the possible values for $N_W$ (which are 2, 3, or 4) against the derived constraint $N_W \le N_L \le 3$ and the condition that every woman has a left-handed person to her right.
If there are 4 women ($N_W=4$), the constraint $N_W \le N_L \le 3$ becomes $4 \le N_L \le 3$. This is impossible, as the number of left-handed people cannot be both greater than or equal to 4 and less than or equal to 3.
Therefore, $N_W=4$ is not possible.
If there are 3 women ($N_W=3$), the constraint $N_W \le N_L \le 3$ becomes $3 \le N_L \le 3$. This means we must have exactly $N_L=3$ and $N_R=3$. Since all women are left-handed ($W \implies L$), the 3 women must be the only left-handed people ($W_1(L), W_2(L), W_3(L)$). Consequently, the remaining 3 people must be men ($N_M=3$), and they must all be right-handed ($M_1(R), M_2(R), M_3(R)$).
Now let's check the condition: "Every woman has a left-handed person to her immediate right."
Consider any arrangement. Let the seats be numbered 1 to 6. If women are placed non-contiguously, e.g., W at 1, 3, 5. Then people at seats 2, 4, 6 must be L. But only the women are L, so seats 2, 4, 6 would have to be occupied by women, which contradicts $N_W=3$.
If women are placed contiguously, e.g., W at 1, 2, 3. Then $W_1(L)$ at 1, $W_2(L)$ at 2, $W_3(L)$ at 3. The person to the right of $W_1$ is $W_2$, who is L (satisfies condition). The person to the right of $W_2$ is $W_3$, who is L (satisfies condition). The person to the right of $W_3$ (at seat 4) must be L. However, seat 4 must be occupied by a man, and we deduced all men must be right-handed. This creates a contradiction.
Therefore, $N_W=3$ is not possible.
If there are 2 women ($N_W=2$), the constraint $N_W \le N_L \le 3$ becomes $2 \le N_L \le 3$. This means $N_L$ can be 2 or 3. If $N_W=2$, then $N_M=4$. Let's check the condition "Every woman has a left-handed person to her immediate right."
Consider the case where the two women sit together: $W_1, W_2$. Let $W_1$ be at seat 1 and $W_2$ at seat 2.
This scenario works perfectly.
The only scenario that satisfies all the given conditions is when there are 2 women.
The number of women at the table is 2.
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78, 65, 82, 69, 86, ?