A car travels 30 km at a uniform speed of 40 km/hr and the next 30 km at a uniform speed of 20 km/hr. Find his average speed.
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A car travels 30 km at a uniform speed of 40 km/hr and the next 30 km at a uniform speed of 20 km/hr.
We have to find the average speed of the car.
Average speed is defined as the ratio of total distance covered with respect to total time taken.
Now,
Total distance covered = Distance covered in (first half + second half)
= 30 + 30 = 60 km
Time = Distance/Speed
t1 = 30/40 hr and t2 = 30/20 hr
Total time taken = t1 + t2
= 3/4 + 3/2
= 3/2(1/2 + 1/1)
= 3/2(3/2)
= 9/4 hr
Average speed = (Total distance covered)/(Total time taken)
Substitute the values in the above formula,
= 60/(9/4)
= 26.67 km/hr
Therefore, the average of the car is 26.67 km/hr.
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