A train travels first 15km at a speed of 30km/h the next 75km/h at a speed of 50 km/h and the last 10km/h at a speed of 20km/h. calculate the avg speed for the entire train journey
Answers
Answer:
Explanation:
Solution,
Here, we have
In 1st part train travels the first 15km at a speed of 30km/h,
We know that,
Speed = Distance/Time
Time = Distance/Speed
So, putting all the values,
t₁ = 15/30 = 1/2 h
Now, next 75 km at a speed of 50 km/h
t₂ = 75/50 = 3/2 h
Now, at last, 10 km at speed of 20 km/h
t₃ = 10/20 = 1/2 h
Here, total time taken,
Total time = 1/2 + 3/2 + 1/2 = 5/2 h
Then, we have to find the total distance travelled by train,
Total distance = 15 + 75 + 20 = 100 km
Now, the final part of the solution,
⇒ Average speed = Total distance/Total time
⇒ Average speed = 100/5/2
⇒ Average speed = 40 km/h.
Hence, the average speed of train is 40 km/h.
Answer:
The av. speed of train is 40 km/hr .
Explanation:
Dist = 15km
speed = 30km/hr
Time = t1
t1 = Dist./speed
= 15/30
= 1/2 hr
Again,
Dist. = 75 km
Speed = 50km /hr
Time = t2
t2 = Dist./Speed
= 75/50
= 3/2 hrs
Again,
Dist. = 10 km
speed = 20 km/hr
Time = t3
t3 = Dist./speed
= 10/20
= 1/2 hr
Now,
Total time taken = t1 + t2 + t3
= 1/2 + 3/2 + 1/2
= ( 1 + 3 + 1 ) / 2
= 5/2 hrs
And,
Total dist. travelled = ( 15 + 75 + 10 ) km
= 100 km
Average speed = dist. travelled/ time taken
= 100/5/2
= ( 100×2)/5
= 20 × 2
= 40 km/hr
Hence,
The Av. speed of train is 40 km/hr .