A train covers 60 km at a speed of 80 km/h, 100 km at a speed of 90 km/h, and another 140 km at a speed of 120 km/h. Find the average speed for the complete journey. (Round to the nearest integer.)
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 99 km/h.
Given that
60 km is covered at the speed of 80 km/h
Hence, time taken = 60 / 80 = 6/8 hours
Another 100 km are covered at the speed of 90 km/h
Hence, time taken = 100 / 90 = 10/9 hours
Another 140 km are covered at the speed of 120 km/h
Hence, time taken = 140 / 120 = 7/6 hours
Average speed = total distance / total time taken
Hence, average speed = (60 + 100 + 140) / () = = 99.08 km/h
Hence, the average speed for the complete journey (Rounded to the nearest integer) is 99 km/h.