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Car drives uphill at 40 km/h and then back downhill at 60 km/h. what is the average speed for the round trip?

Sagot :

Answer:

48 km/hr

Explanation:

These are often calculated incorrectly because TIME is ignored

time = distance / rate

               uphill =  d / 40       downhill = d/60

average rate =   distance / time

                      =   2d / ( d/40 + d/60)              2d is uphill + downhill

                        = 2 / ( 1/40 + 1/60 ) =   48 km/hr