SOLUTION: a train travel 68 km/h at an average speed of 51 km/h.It than travel another 20 km at an average speed of 40 km/h before reaching its destination. Calculate the average speed for t

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: a train travel 68 km/h at an average speed of 51 km/h.It than travel another 20 km at an average speed of 40 km/h before reaching its destination. Calculate the average speed for t      Log On

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Question 884857: a train travel 68 km/h at an average speed of 51 km/h.It than travel another 20 km at an average speed of 40 km/h before reaching its destination. Calculate the average speed for the whole journey.
Answer by JulietG(1812) About Me  (Show Source):
You can put this solution on YOUR website!
At 51kmh, the train would need to travel 11%2F3hours to cover 68km. [68-51= 17. 17 is 1%2F3of 51.]
At 40kmh, the train would need to travel 1%2F2hour to cover 20km [20/40]
Total travel time is 15%2F6hours (or 1 hour 50 minutes).
In that time, total distance is 88km
88km / 1.8333 (converted the fraction to decimal for ease of use) = 48kmh average speed.