A truck travels at an average speed of 45 km/h over a distance of 105 km. It then travels another 85 km at a higher average speed. His overall average speed for the entire trip is 55 km/h. What was his average speed for the second stage?

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Answer 1 · 2018-04-12T13:51:20

The average speed is #=75.8kmh^-1#

Total distance travelled is #d=105+85=190km#

The average speed is #barv=55kmh^-1#

The time taken for the entire trip is

#t=d/barv=190/55=3.456h#

The time taken for the first part is

#t_1=105/45=2.333h#

The time taken for the second part is

#t_2=3.455-2.333=1.122h#

The average speed for the second part is

#v_2=85/1.122=75.8kmh^-1#