A motorcyclist covers 1/3 of a given distance with a speed of 10 km/h, the next
1/3 at a speed of 20 km/h& last 1/3 at 30 km/h. Find his average speed for the entire
journey.
Answers
Answer:
16.36 km/hr
Explanation:
Let the total distance be 3d.
• speed = distance/time
1/3 of 3d is d, in each interval it covers d.
For first 1/3 rd:
= > d/time = 10
= > d/10 = time
For second 1/3 rd:
= > d/time = 20
= > d/20 = time
For third 1/3 rd:
= > d/time = 30
= > d/30 = time
Total distance = 3d
Total time = (d/10) + (d/20) + (d/3)
= > total time = (6d+3d+2d)/60
= > Total time = 11d/60
Thus,
Speed = total distance/total time
= 3d/(11d/60)
= > 180/11
= > 16.36 km/hr
Answer:
16.36 km/hr
Explanation:
A motorcyclist covers 1/3 of a given distance with a speed of 10 km/h, the next 1/3 at a speed of 20 km/h& last 1/3 at 30 km/h.
Time = Distance/Speed
Assume that the distance covered by the motorcyclist is x.
Case 1)
→ t1 = x/10 hr
Case 2)
→ t2 = x/20 hr
Case 3)
→ t3 = x/30 hr
Total distance covered = x + x + x = 3x
Total time taken = t1 + t2 + t2
= x/10 + x/20 + x/30
= (6x + 3x + 2x)/60
= 11x/60
Hence,
Average speed = (Total distance covered)/(Total time taken)
= 3x/(11x/60)
= 180/11
= 16.36 km/hr