Distance between Gondia to Nagpur is 150 km. A man cover first 60 km at speed of 60 km/hour, next 48 km he cover at speed of 80 km/hour and remaining distance he cover at speed of 70 km/hour then find the approximate average speed of the man for whole journey.?

Option 2 : 68 km/hour

Given:

Total distance = 150 km

Speed for first 60 km = 60 km/hour

Speed for next 48 km = 80 km/hour 

Speed for remaining 42 km = 70 km/hour

Formula used:

Speed = Distance\Time

Calculation:

Let T₁, T₂ and T₃ be the time required for speed 60 km/hour, 80 m/hour and 70 km/hour respectively

According to question

Time = Distance/Speed

⇒ Time, T₁ = 60/60

⇒ T₁ = 1 hour      ---(1)

⇒ Time, T₂ = 48/80

⇒ Time, T₂ = 0.6 hour      ----(2)

⇒ Time, T₃ = 42/70

⇒ Time, T₃ = 0.6 hour      ----(3)

⇒ Total time = T₁ + T₂ + T₃

⇒ Total time = 1 + 0.6 + 0.6

⇒ Total time = 2.2 hour

Average speed = Total distance/Total time

⇒ Average speed = 150/2.2

⇒ 68.18 km/hour

⇒ 68 km/hour                          

∴ The average speed of man for the whole journey is 68 km/hour