We are reaching the end. Here is the 4th logic puzzle:
A girl is at the center of a circular lake of radius R and a man at the perimeter. The man desperately wants to catch the girl. The only way the girl can escape is to reach the perimeter of the lake and run away. Swimming speed of the girl is S. Running speed of girl and man is 4S. What strategy/path should the girl follow to guarantee a safe escape?