Multiple choice

A man can row 12 km/hr in still water. If the speed of the current is 3 km/hr, he takes 4 hours more in upstream than in the downstream. What is the distance (in km)? एक आदमी स्थिर जल में 12 किमी / घंटा की चाल से तैर सकता है। यदि धारा की चाल 3 किमी / घंटा है, वह ऊर्ध्वप्रवाह में अनुप्रवाह की अपेक्षा 4 घंटे अधिक लेता है। दूरी (किमी में) क्या है?

  1. 30

  2. 45

  3. 60

  4. 90
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Downstream speed = 12 + 3 = 15 km/hr. Upstream speed = 12 - 3 = 9 km/hr. Let distance = d. Then d/9 - d/15 = 4, giving (5d - 3d)/45 = 4, so 2d = 180 and d = 90 km. The time difference of 4 hours arises because upstream is slower. Options A, B, and C are incorrect distances.

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