Half of the total journey is covered at the speed of 90 km/hr, while 1/3 of total journey is covered at the speed of 75 km/hr and 1/6 of total journey is covered at the rate of 50 km/hr. Find the average speed of the whole journey in m/s if distance of total journey is 900 km.
Half of the total journey is covered at the speed of 90 km/hr, while 1/3 of total journey is covered at the speed of 75 km/hr and 1/6 of total journey is covered at the rate of 50 km/hr. Find the average speed of the whole journey in m/s if distance of total journey is 900 km. Correct Answer <span style=" line-height: 115%; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">125/6 m/s</span>
Given:
Total journey = 900 km
Half of total journey is covered at the speed of 90 km/hr
1/3 of total journey is covered at the rate of 75 km/hr
1/6 of total journey is covered at the rate of 50 km/hr
Concept used:
Average speed = Total Distance/Total time taken
Speed in m/s = speed in km/hr × 5/18
Calculation:
Total journey = 900 km
Half of the total journey = 450 km
⇒ 450 km is covered at the rate of 90 km/hr
⇒ Time taken to cover 450 km = 450/90 = 5 hours
Now, 1/3 of total journey = 300 km
⇒ 300 km is covered at the rate of 75 km/hr
⇒ Time taken to cover 300 km = 300/75 = 4 hours
Now, 1/6 of the total journey = 150 km
⇒ 150 km is covered at the rate of 50 km/hr
⇒ Time taken to cover 150 km = 3 hours
Now, Total time taken to cover whole journey = (5 + 4 + 3) hours
⇒ Total time taken = 12 hours
Average speed of the whole journey = 900/12
⇒ Average speed of the whole journey = 75 km/hr
Speed in m/s = speed in km/hr × 5/18
⇒ As we know, Speed in m/s = speed in km/hr × 5/18
⇒ Speed in m/s = 75 × 5/18
⇒ 125/6 m/s