Answer
For the boat to make a trip directly across the river, the velocity of water relative to ground is perpendicular to velocity of boat relative to ground. In a right angle triangle, the net velocity ie. velocity of boat relative to water is greatest.
But the problem states otherwise. As per the problem, the speed of water is higher than the speed of the boat relative to the water. This is not possible.
Work Step by Step
For the boat to make a trip directly across the river, the velocity of water relative to ground is perpendicular to velocity of boat relative to ground. In a right angle triangle, the net velocity ie. velocity of boat relative to water is greatest.
But the problem states otherwise. As per the problem, the speed of water is higher than the speed of the boat relative to the water. This is not possible.