Question

Akbar Travels 100 km at a speed of 60 km per hour and returns at 40 km per hour calculate the average speed for the whole journey

Answer 1

Hi.

Here is your answer---

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Let the Akbar goes fro Place A to Place B.
Given---

Starting Journey of Akbar,

Distance between the two Places A and B is 100 km.

Speed of the Akbar to goes from A to B= 60 km/hr.

Using the Formula,
 
      Speed = Distance/Time
       
       Time(t1) = Distance/Speed
                 = 100/60
                 = 10/6
                 = 5/3 hr.

Returning Journey Of Akbar,

Distance between B and A = 100 km.

Speed of Akbar while traveling from B to A = 40 km/hr.

Thus, Time(t2) = 100/40
                        = 10/4
                        = 5/2 hrs.

For Average Speed,

 Total Distance = 100 + 100
                        = 200 km.

Total Time = 5/3 + 5/2
                 = (10 + 15)/6           [Taking L.C.M.]
                 = 25/6 hrs.

Using the Formula,

     Average Speed = Total Distance/ Total Time
                              = 200/(25/6)
                              = 8 × 6
                             = 48 km/hr.

Thus, the average speed of the Akbar is 48 km/hr.

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Hope it helps.

Have a nice day.