Question

Abau Abdul while driving to school computers the
average for his route to be 20 km/hr. On his traffic
and his average speed is 30 km / hr what is the
average
speed for
Abdul's trip?​

Answer 1

Abdul while driving to school computers the average for his route to be 20 km/hr.

Let us assume that the distance covered by the Abdul is 'x'.

Distance = Speed × Time

d1 = s1 × t1

x = 20 × t1

x/20 = t1 ..............(1st equation)

Also, during traffic his average speed is 30 km/hr.

d2 = s2 × t2

x = 30 × t2

x/30 = t2 ..............(2nd equation)

Average speed is defined as the ratio of total distance covered with respect to total time taken.

Total distance covered by the Abdul = (x + x)km = 2x km

Total time taken = t1 + t2

= x/20 + x/30

= (3x + 2x)/60

= 5x/60

Average speed = 2x/(5x/60)

= (2x × 60)/5

= 24

Therefore, the average speed of the Abdul during the trip is 24 km/hr.

Answer 2

Correct Question -

Abdul while driving to school computes the average speed of the trip to be 20 kmph .

On his return trip along the same route , there is less traffic and the average speed is 30 kmph .

What is the average speed for Abdul ' s trip ?

Solution -

See the attached diagram ....

In the above Question , the following information is given -

Abdul while driving to school computes the average speed of the trip to be 20 kmph .

On his return trip along the same route , there is less traffic and the average speed is 30 kmph .

So ,

The innitial average speed is 20 kmph .

The final average speed is 30 kmph .

Let the distance between Abdul ' s home and his school be D metres .

Total distance covered by Abdul = 2 D

We also know the following formula -

Speed = [ Total Distance Covered ] / [ Total time taken ]

So ,

20 = [ D ] / [ T 1 ]

=> T 1 = [ D ] / 20

30 = [ D] / [ T 2 ]

=> T2 = [ D ] / 30

Total time taken for the whole trip

=> T 1 + T 2

=> D / 20 + D / 30

=> ( 5 D ) / 60

Now , Similarly -

Average Speed = [ Total Distance Covered ] / [ Total time taken ]

=> Average speed

=> [ 2 D ] / [ ( 5 D / 60 )

=> 24 kmph .

Hence the average speed for Abdul ' s trip is 24 kmph ...

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