car cover one third distance with a speed of 30 km per hour and remaining distance with the speed of 54 km per hour find average speed
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Answer:
42.63 km/ hr
Step-by-step explanation:
Let the total distance be 'x'
In 1st case ,
Speed = 30 km/hr ; Distance = x/3 km
Time taken = x/3 ÷ 30 = x/90 hr
In 2nd case,
Speed = 54km/hr ; Distance = 2x/3 km
Time taken = 2x/3 ÷ 54 = x/81 hr
Avg. speed = Total distance / Total time taken
= x ÷ ( x/90 + x/81 )
= x ÷ ( 19x / 810 )
= 810/19
= 42.63 km / hr
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