1man60kg 1man 55kg 1boy 30kg 1boy35kg 1 dog 12kg have to cross river canoe can only carry 75kg at one time how many crossing to move them all from one side to the other
To solve this puzzle, we need to find a way to transport all the individuals across the river using a canoe that can carry a maximum weight of 75kg. Here's an explanation of the process:
1. First, let's focus on the heaviest individuals: the two men weighing 60kg and 55kg. Since the canoe can only carry a maximum of 75kg, both men cannot cross together. Therefore, one of the men weighing 60kg should be transported on the first trip.
2. After dropping off the 60kg man on the other side, the canoe returns to the original side empty. Now, let's consider who should go on the second trip.
a) If the 55kg man goes alone, there will be a total weight of 55kg on the canoe.
b) If the 30kg boy goes alone, there will be a total weight of 30kg on the canoe.
c) If the 35kg boy and the 12kg dog go together, there will be a total weight of 35kg + 12kg = 47kg on the canoe.
Since 55kg is the closest weight to the maximum capacity of 75kg, the 55kg man should go on the second trip.
3. After dropping off the 55kg man on the other side, the canoe returns to the original side empty. Now, we have three remaining options for the third trip:
a) The 30kg boy goes alone, with a total weight of 30kg.
b) The 35kg boy goes alone, with a total weight of 35kg.
c) The 35kg boy and the 12kg dog go together, with a total weight of 35kg + 12kg = 47kg.
Since the 30kg boy is the lightest remaining individual, he should go on the third trip alone.
4. After dropping off the 30kg boy on the other side, the canoe returns to the original side empty. Now, we only have two individuals left: the 35kg boy and the 12kg dog. They both weigh a combined 35kg + 12kg = 47kg, which is less than the maximum capacity of the canoe.
Therefore, the last trip involves taking the 35kg boy and the 12kg dog together.
In total, we needed three trips to transport all the individuals across the river.