On a float trip, Arjun traveled 37 miles downstream in the same amount of time that it would take him to row 18 miles upstream. If the speed of the current is 2 mph, find his speed in still water.

Respuesta :

Answer:

  5 15/19 ≈ 5.79 mph

Step-by-step explanation:

You want Arjun's speed in still water if he traveled 37 miles with the 2 mph current in the same time it would take him to travel 18 miles against the current.

Setup

The relationship between time, speed, and distance is ...

  t = d/s

Since the two times are the same, we have ...

  [tex]\dfrac{37}{x+2}=\dfrac{18}{x-2}[/tex]

where x represents Arjun's speed in still water.

Solution

Multiplying the equation by (x+2)(x-2) gives ...

  37(x -2) = 18(x +2)

  37x -74 = 18x +36 . . . . eliminate parentheses

  19x = 110 . . . . . . . . . . . . add 74 -18x

  x = 110/19 = 5 15/19 ≈ 5.79 . . . . mph

Arjun's speed in still water is 5 15/19 mph, about 5.79 mph.

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Additional comment

The travel time in each direction is 4.75 hours.