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  • A train travels at a certain average speed for a distance of 63 km and then travels at a distance of 72 km at an average speed of 6 km/hr more than its original speed. If it takes 3 hours to complete total journey, what is the original average speed?</

A train travels at a certain average speed for a distance of 63 km and then travels at a distance of 72 km at an average speed of 6 km/hr more than its original speed. If it takes 3 hours to complete total journey, what is the original average speed?

 

 

Answers (1)

Let the original average speed of the train is x

Then (x+6) will be the new speed for the remaining 72 Km 

complete travel  time = 3 hrs 

 Therefore 

\frac{63}{x} + \frac{72}{x+6} = 3 \\\ \ x^2 -39 x - 126 = 0 \\\\ = ( x -42 ) (x+3 ) = 0 \\\\ x = 42 , x \neq -3

the original speed of the train is 42 km /hr 

Posted by

Safeer PP

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