Multiple choice

Speed of a boat in still water is 7 kmph and the speed of the stream is 1.5 kmph. A distance of 23.1 km, going upstream is covered in एक नाव की स्थिर जल में चाल 7 किमी./घंटा है और धारा की चाल 1.5 किमी./घंटा है | 23.1 किमी. की दूरी को धारा के प्रतिकूल तय करने में लगा समय है

  1. 3 hours 45 minutes/3 घंटे 45 मिनट

  2. 3 hours 36 minutes/3 घंटे 36 मिनट

  3. 4 hours 12 minutes/4 घंटे 12 मिनट

  4. 6 hours 36 minutes/6 घंटे 36 मिनट
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C Correct answer
Explanation

Upstream speed = boat speed in still water - stream speed = 7 - 1.5 = 5.5 kmph. Time = Distance / Speed = 23.1 / 5.5 = 4.2 hours = 4 hours 12 minutes (0.2 hour = 12 minutes). Always subtract stream speed when going upstream.

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