Question

Akshil drove his car with speed of 20km/h while going to his college. When he turned to his home along the same route, the speed of car is 30km/h. Calculate the average speed of the car during entire journey.

Answer 1

Let the distance travelled by Akhil be s km .
Time taken by Akhil while going to the college = t1 = s/30 hr
Time taken by Akhil while coming from the college =t2 = s/20 hr
Total time taken = t1 + t2 =t = ( s/30) + (s/20)
Total distance travelled = 2s
Average speed = Total distance travelled /total time taken
= 2s/ [ ( s/30) + (s/20)]
= 2 / (1/12)
= 24km/hr
Hence the average speed of the car = 24km/hr

Answer 2

Answer: Time taken while going= t1=x/30

Time taken while coming=t2=x/20

Total time taken = t1+t2(x/30+x/20) hr

Total Distance=2x

Average speed=Total Distance/Total Time

= 2x/x/30+x/20

= 2/1/12

=24kmph