Two women (Amy and Beatrice) and three men (Charles, Dennis and Ethan) have to
row across a river in a small boat that can only sit two people at the most.
They want to cross the river using the least number of crossings.
b. Only one person will row the boat during each crossing.
c. The women request that no woman will be left alone with a man (or men) at any
time.
d. The men request that no one will row the boat twice in two consecutive crossings.
e. Of those who will row while alone in the boat, Charles will be the first, Dennis
will be the second and Ethan will be the third.
Who will be the last person to row across the river?
Well, since Charles, Dennis, and Ethan will take turns rowing the boat while alone, that leaves Amy and Beatrice to be rowed across by the men.
So, if Charles rows Amy across first, Dennis will row back alone. Next, Charles will row Beatrice across, and Ethan will row back alone. Then, Dennis will row Amy back across, leaving Charles to row Beatrice across for the final crossing.
Therefore, Amy will be the last person to row across the river. But hey, at least she'll have some quality boat time to herself!
Based on the given conditions, let's analyze the steps to determine who will be the last person to row across the river:
1. Charles must be the first person to row alone in the boat.
2. After Charles crosses the river, he cannot row again in the next crossing, so one of the women must row with him. Let's assume that Amy rows with Charles.
3. Now, there are three people (Beatrice, Dennis, and Ethan) on the starting side of the river. Since the women request that no woman will be left alone with a man (or men) at any time, either Beatrice or Dennis must row the boat alone.
4. According to condition e, Dennis will be the second person to row alone in the boat.
5. After Dennis crosses the river, either Beatrice or Ethan must row the boat back alone.
6. Finally, Beatrice will be the last person to row across the river.
So, the last person to row across the river will be Beatrice.
To determine the last person to row across the river, let's go through each step and eliminate the options based on the given conditions.
Let's start with condition (e), which states that Charles will be the first to row, followed by Dennis and then Ethan. We can deduce that Amy and Beatrice will not be in the first three crossings since they are women, and it is mentioned that only one person rows the boat during each crossing.
Now let's consider condition (c), which states that no woman should be left alone with a man or men at any time. Since Charles will be the first person to row, there are no women left alone in the boat in the first crossing.
Based on condition (d), no one can row the boat twice in two consecutive crossings. Since Charles is the first to row, he cannot row in the second crossing. Hence, Charles will not be part of the second crossing.
Considering conditions (c) and (d), we can conclude the following:
First crossing: Charles rows the boat alone.
Second crossing: Dennis must row with a woman since Charles cannot row again. Amy or Beatrice will row with Dennis to fulfill condition (c). Ethan cannot row since he should be the third person to row, as per condition (e).
Now let's move on to the third crossing. It is mentioned that Ethan will be the third person to row. Therefore, Dennis cannot row again, so it must be Amy or Beatrice who row with Ethan in the third crossing to fulfill condition (c).
After the third crossing, we have the following remaining people who have not yet crossed:
- Charles and Dennis: Charles cannot row again since he has already rowed once, and Dennis cannot row again since he has already rowed twice.
- Amy and Beatrice: Only one of them can join Charles or Dennis for the remaining crossing(s) because condition (c) states that no woman is left alone with a man.
Based on the above analysis, we can deduce the following order of crossings:
1. Charles rows alone.
2. Dennis with Amy/Beatrice (either one).
3. Ethan with Amy/Beatrice (the other one).
4. Charles with Dennis.
Therefore, the last person to row across the river will be Charles.