How far did he swim?

Question

A river is 10.5 meters wide and its banks are parallel to each other. John tries to swim straight across, but the current pushes him downstream so that he lands 14 meters from the spot he wanted to reach. How far did he swim ?

Answer 1

Hi Desi, using the Pythagorean Theorem, we can find how far John swam.

 

Let a represent the width of the river, or 10.5 meters. Let b represent the distance John was from his original stopping point.

 

Let c represent how far John actually swam.

 

a² + b² = c²

 

10.5² + 14² = c²

 

110.25 + 196 = c²

 

c² = 306.25

 

c = ±17.5

 

We can discard the negative result lose any ground upstream.

 

John swam 17.5 meters.

 

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