Question
A motor car travels a distance of 180 km at the speed of
20 kmph. If it covers the next 100 km of its journey at the speed of 20 kmph and last 40 km of its journey at the speed of 20 kmph. What is the average speed of the car?Solution
D 1= 180 Km, S1= 20 Km/hr, D2= 100 Km, S2 = 20 Km/hr, D3= 40 Km, S3= 20 km/hr. T1 = Distance/Speed = 180/20 = 9hr T2 = Distance/Speed = 100/20 = 5hr T3 = Distance/Speed = 40/20 = 2hr Average speed = Total distance/Total time = 320/16 = 20 km/hr
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