Multiple choice

Speed of boat in still water is 15 kmph, speed of current is 25% less than speed of boat. If it took total 16 hours to go to a place and come back then find the total distance covered by it. शान्त जल में नाव की चाल 15 किमी/घंटा है, धारा की चाल नाव की चाल से 25% कम है। यदि इसे एक स्थान तक जाने में तथा वापस आने में कुल 16 घण्टे लगते है तो इसके द्वारा कुल चली गयी दूरी ज्ञात कीजिये।

  1. 92 km/किमी

  2. 105 km/किमी

  3. 112 km/किमी

  4. 120 km/किमी
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B Correct answer
Explanation

Speed of boat in still water = 15 kmph. Speed of current = 75% of 15 = 11.25 kmph. Downstream speed = 15 + 11.25 = 26.25 kmph. Upstream speed = 15 - 11.25 = 3.75 kmph. Let distance be d. d/26.25 + d/3.75 = 16. Solving: d(1/26.25 + 1/3.75) = 16, which gives d = 52.5 km. Total distance = 2d = 105 km.

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