Question

A man travels 24 km at 6 km/h,
another 24 km at 8 km/h and also
third 24 km at 12 km/h. Find the
average speed (in km/h) for the
whole journey.
​

Answer 1

Answer :-

• The average speed of the man is 8km/h.

Step-by-step explanation :-

To Find :-

• The average speed for the whole journey.

Solution :-

Given that,

• Distance covered by man ( d₁ ) = 24km
• Speed = 6km/h

First we need to find out the time taken by the man,

Therefore,

Time taken ( t₁ ) = Distance ÷ Speed

=> 24/6

=> 4 hours

• Another distance covered by man = 2km
• Speed = 8km/h

Therefore,

Time taken ( t₂ ) = Distance ÷ Speed

=> 24/8

=> 3 hours

• Then, distance covered by man = 24km
• Speed = 12km/h

Therefore,

Time taken ( t₃ ) = Distance ÷ Speed

=> 24/12

=> 2 hours

According the question,

Now, the average speed of the man is,

As we know that,

Average speed = Total distance ÷ Total time,

=> ( d₁ + d₂ + d₃ ) ÷ ( t₁ + t₂ + t₃ )

=> ( 24 + 24 + 12 ) ÷ ( 4 + 3 + 2 )

=> ( 48 + 12 ) ÷ ( 7 + 2 )

=> 72 ÷ 9

=> 8

The average speed of the man is 8km/h.