Multiple choice

A boat can travel 8 km/hr in still water. If the river is flowing at 3 km/hr, it takes 3 hours more to go to a certain point upstream than to go downstream for the same distance. How far is the point?

  1. 25 km

  2. 27.5 km

  3. 31 km

  4. 33.5 km

  5. 35.5 km
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let distance be D. Downstream speed = 8+3=11, Upstream speed = 8-3=5. Time difference = D/5 - D/11 = 3. (11D - 5D) / 55 = 3. 6D = 165. D = 27.5 km.

AI explanation

Using the boat and stream formula, the upstream speed is 8 minus 3, which equals 5 kmph, and the downstream speed is 8 plus 3, which equals 11 kmph. Let the distance be D, so the time difference equation is D divided by 5 minus D divided by 11 equals 3 hours. Finding a common denominator gives 6D divided by 55 equals 3, which means D equals 165 divided by 6. The distance is 27.5 km.

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