Multiple choice

A person rows in still water with 8 km/hr. If the speed of the current is 2 km/h, it takes 2 hours more in upstream than in the downstream for the same distance. What is the distance?

  1. 24 km

  2. 30 km

  3. 18 km

  4. 36 km

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Speed downstream = 8 + 2 = 10 km/h, upstream = 8 - 2 = 6 km/h. Let distance be d km. Time downstream = d/10, upstream = d/6. Given: d/6 - d/10 = 2 hours. Solving: d(1/6 - 1/10) = 2, so d(5/30 - 3/30) = 2, d(2/30) = 2, d = 30 km. Verification: Downstream 30/10 = 3h, upstream 30/6 = 5h, difference = 2h.

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