The swimming pool in an exclusive club is a circular strip. A water flow is artificially maintained in the strip, along a clockwise direction, at a constant speed of 3km/h(kilometers/hour). One morning, Ayub and Rana start swimming at the same time from two diametrically opposite points on the strip. Ayub swims in a counterclockwise direction, while Rana swims in a clockwise direction. They swim at constant, but different, speeds. When they meet for the first time, Ayub has covered 60m(meters). They meet again after Rana has covered 180m from the first meeting point.
If Rana swims at the speed of 3 km/h in still water, how long does Ayub take to complete one round of the circular strip, if he swims in the clockwise direction?
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Step-by-Step Solution
Key idea: This is a circular motion problem with a current, requiring careful handling of effective speeds and relative distances.
Step 1: Convert all speeds to consistent units. Water flow speed = 3 km/h = 50 m/min.
Step 2: Rana's speed in still water is 3 km/h = 50 m/min. Since Rana swims clockwise (with the flow), Rana's effective speed is m/min.
Step 3: Let Ayub's speed in still water be km/h. Ayub swims counterclockwise (against the flow), so Ayub's effective speed is km/h.
Step 4: They start from diametrically opposite points, so the initial distance between them is , where is the circumference.
Step 5: At the first meeting, Ayub covers 60 m. The time taken is , where is Ayub's effective speed in m/min.
Step 6: In this same time, Rana covers meters.
Step 7: The sum of their distances is , so .
Step 8: They meet again after Rana covers 180 m. The time for this second leg is minutes.
Step 9: In this time, together they cover the full circumference . So, .
Step 10: Equate the two expressions for : .
Step 11: Solving this yields m/min (which corresponds to km/h).
Step 12: Substitute back to find : m. Wait, m. Let's re-verify: ? No, . But .
Correction: The relative speed is the sum of their still water speeds! km/h.
Let's use km/h. . Rana covers .
.
hours. .
.
Let . .
So km/h.
Step 13: If Ayub swims clockwise, his effective speed is km/h = m/min.
Step 14: km = 300 m.
Step 15: The time to complete one round is minutes, which is 1 minute 48 seconds.
Answer: 1 minute 48 seconds