Question

Bus travels a distance of 120 km with a speed of 40 km/h and returns with a speed of 30 km/h. Calculate the average speed for the entire journey.

Answer 1

Answer:

Average speed = 34.28 km/h

Step by step explanations :

Given that,

Bus travels a distance of 120 km

with a speed of 40 km/h

and

returns with a speed of 30 km/h.

here,

total distance travelled = 2 × 120

= 240 km

Time taken to cover 120 km

at speed 40 km/h

= 120/40

= 3 hr

Time taken to cover 120 km

at speed 30 km/h

= 120/30

= 4 hr

Average speed

=total distance travelled/total time taken

Total distance covered = 240

Total time taken = 3 + 4

= 7 h

Average speed = 240/7

= 34.28 km/h

so,

Average speed = 34.28 km/h

Answer 2

• Distance travelled by bus = 120 km

• Speed = 40 km/hr.

• Bus returns with a speed = 30 km/hr.

_____________ [ GIVEN ]

• We have to find the average speed for entire journey.

_____________________________

Distance = 120 km

So,

Total distance travelled = 2 × 120

=> 240 km

(Because bus goes with speed 40 km/hr and returns with speed 30 km/hr. So, distance is two times of the total distance.)

Time taken to cover 120 km at speed 40 km/h

Time = $\dfrac{Distance}{Speed}$

=> $\dfrac{120}{40}$

=> 3 hr.

Time taken to cover 120 km at speed 30 km/h

=> $\dfrac{120}{30}$

=> 4 hr

Now..

» Average speed = $\frac{Total\: distance\: travelled}{Total \:time \:taken}$

Total distance covered = 240

Total time taken = 3 + 4 = 7 hr.

Put the values in above formula

Average speed = $\dfrac{240}{7}$

=> 34.28571 km/hr.

=> 34.29 km/hr (approx.)

____________________________

34.29 km/hr. is the average speed for entire journey.

__________ [ ANSWER ]

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