A 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.
Answers
In first case:
S1 = 120Km
V1 = 40Km/h
T1 = 120/40 = 3hr.
In second case:
S2 = 120km
V2 = 30km/h
T2 = 120/30 = 4hr
total time takn= 3+4=7hr
Total distance covered = 120+120 = 240km
Average speed = Total distance covered/Total time taken = 240/7=34.28Km/hr.
Answer:
Distance travelled is 120 km .
When the bus travels with 40 km/hr ,
Time = distance / speed
⇒ Time = 120 km/40 km/hr
⇒ Time = 3 hr
When the bus travels at 30 km/hr ,
Time = Distance / speed
⇒ Time = 120 km / 30 km/hr
⇒ Time = 4 hr
Total time taken is 4 hr + 3 hr = 7 hr .
Total distance taken will be 120 km + 120 km = 240 km
Average speed = Total distance / Total time
⇒ Average speed = 240 km / 7 hr
⇒ Average speed = 34.2857 km/hr
⇒ Average speed = 34.29 km/hr
The average speed is 34.29 km/hr .
Explanation:
The average speed is the total distance divided by the total time .
We can calculate the total time by adding the time in both cases .
Time is calculated by :
Time = Distance / speed .