contestada

A sportsman can run 320 feet down a sand dune in 20 seconds. He can run 240 feet up the sand dune in 60 seconds.
How fast can the sportsman run in the sand on level​ ground?

Respuesta :

320 /20 = 16' per second

240/ 60 = 4' per second

Let his speed on level ground be  x ' per second

Let force of gravity be  g ' per second

DOWN the sand dune =  x + g = 16

UP      =                             x - g = 4

ADD

2x = 20

x = 10

ANSWER 10' per second.

(all credit goes to ranjankar at yahoo answer)

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