A and B are two fixed spots in a river in which water has a steady speed . A person who can swim

with a speed v relative to water swims from A to B and back to A along the shortest path. if the water is still, the person will take a time 30 minute in swimming from A to B and back to A along the shortest path. But we know that water is actually not still. The person also knows the technique of just flowing with water without exerting his own effort. Using this technique, i.e., just being carried with water, he takes a time 20 minute in moving from A to B. As shown, X and Y are two places directly opposite to each other on opposite banks. Assuming that width of the river is the same as the distance between A and B, answer these questions. (assume ) Time taken by the person to swim from A to B (in running water) if the person uses his own effort also, will be nearly