A journey of 900 km is completed in 11 h. If two-fifth of the journey is completed at the speed of 60 km/h, at what speed (in km/h) is the remaining journey completed?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 108
Concept Used:
Distance = speed × time
Average speed = Total Distance/Time Taken
Explanation:
The average speed of the journey = 900/11 kmph
According to the question,
Total distance = 900 km
He traveled 2/5 of the total distance at 60 kmph. Distance traveled = (2/5) × 900 = 360 km
Thus, Time taken to travel this distance = 360/60 = 6 hours
Time taken to travel the remaining 540 km = 540/s, where 's' is the speed with which he covered this distance.
Average speed = 900/{6 + 540/s}
⇒ 900/11 = 900/{6 + 540/s}
⇒ 6 + 540/s = 11 ⇒ 540/s = 5
⇒ 540/5 = s
Thus, s = 108 kmph
Hence, the remaining journey is completed with the speed of 108 kmph.