Question

A person travels a total distance in three parts in the ratio 4:3:1 with a constant speed of 90 km h-!, 20 m-1 and 10 m s , respectively. What is the average speed of the person while journey? m​

Answer 1

Answer:

Explanation:

Let the distances travelled be 4x, 3x and x.

So, First part of distance 4x is travelled with speed of 90 km/hr (90*5/18 = 25 m/s).

The second part of distance 3x is travelled with speed of 30 m/s.

The third part of distance x is travelled with speed of 10 m/s.

Now, Finding the time in each case.

Case 1 :

Time = 4x/25 s

Case 2 :

Time = 3x/30 s

Case 3 :

Time = x/10 s

Average Speed = Total Distance/Total Time

⇒ Avg. Speed = (4x + 3x + x)/(4x/25 + 3x/30 + x/10)

⇒ Avg. Speed = 8x/(24x + 15x + 15x)/150

⇒ Avg. Speed = 8x/(54x/150)

⇒ Avg. Speed = 8x*150/54x

⇒ Avg. Speed = 150/6.75

⇒ Avg. Speed = 22.22 m/s

Average Speed of the journey is 22.22 m/s.

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