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How to solve problem, "A boat travels dwnstream m nautical miles at d knots and then travels back upstream m nautical miles at u knots. What is average speed for entire trip?"? The answer is 2ud/(u+d)konts

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  • lonboo12
  • ベストアンサー率48% (171/352)
回答No.3

The way to solve these formula is the same as the way of thinking in "How to solve for speed, time, and distance". m nautical miles =distance d knot or u knot = speed So,It's easy to solve if you draw a diagram like below one! m nautical miles m nautical miles --------------------------|-------------------------- d knot u knot Then, to find the average of this entire process, You simply multiply it by two and divide it to get the average value.

  • asuncion
  • ベストアンサー率33% (2127/6289)
回答No.2

The total travel distance = 2 * m miles. So, the answer is: (2 * m) / (m / d + m / u) = (2 * u * d) / (u + d)

  • hiro_1116
  • ベストアンサー率30% (2576/8333)
回答No.1

It is a quite simple. The total traveling distance is 2m. The time for round trip is (m/d)+(m/u). Then, the average speed is 2m/((m/d)+(m/u)).

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