Ann entered a race which required a run of 10 km north and a bike of 120 km west. Determine her running speed if she cycled ten times faster than she ran and the total race took her four hours to complete.



Answer :

x - running speed
10x - speed on bike

v = s/t
s - distance
t - time

t = s/v

s₁ = 10 km
s₂ = 120 km

[tex]\frac{10}{x} + \frac{120}{10x} = 4\\\\\frac{10}{x} + \frac{12}{x} = 4\ \ //*x\\\\10 + 12 = 4x\\\\4x = 22\ \ //:4\\\\x =\frac{22}{4} = 5,5\ km/h[/tex]

Solution:
Running speed = 5,5 km/h

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