Aboy and his dog are out for a morning excursion to the river, whichis located 4.0 km away. the boy walks briskly at 2.0 m/s in a straight line. the dog isunleashed and runs back and forth at 4.5 m/s between the boy and the river, until bothreach the river. what is the distance run by the dog?

9 Km

Explanation:

given,

distance of the river = 4 Km = 4000 m

speed of the boy = 2 m/s

speed of the dog back and forth = 4.5 m/s

distance ran by the dog = ?

time taken by the boy to cover the distance

we know,

distance = speed x time

t = 2000 s.

now, distance travel by the dog.

d= 4.5 x 2000

d = 9000 m

d = 9 Km

distance covered by the dog is equal to 9 Km.

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