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Mr Lee drove at a speed of 60km/h for 150km.He then drove the remaining 120km at a speed of 80km/h.Find his average speed for the whole journey.

Respuesta :

Answer:

Step-by-step explanation:

Total distance / total time = average speed

total distance = 150 + 120 = 270 km

time at 60 km/hr :   150 km / 60 km / hr = 2.5 hr

time at 80 km/hr :   120 km / 80 km / hr = 1.5 hr

  total time = 2.5 + 1.5 = 4 hours

total distance / total time = 270 km / 4 hr = 67.5 km/hr average

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