In a race around a circular track, an athlete runs at 10 m/sec in the first round, at 20 m/sec in the second round, and at 30 m/sec in the third round. Find his average speed (in m/sec) for the race. (correct to 2 decimal places)
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e.16.36
Let the circular track length be x meter
⇒ Time taken by A = x/10
⇒ time taken by B = x/20
⇒ Time taken by C = x/30
The average speed = Total distance covered/time taken
= (x + x + x)/{(x/10) + (x/20) + (x/30)}
= 3x/{11x/60)
= 180x/11x = 16.36 m/s.