Bob's school track is 400 meters. If Bob ran the first lap in 70 seconds, the second and third lap in 85 seconds each, what was his average speed in (m/s) for his entire run?
If each lap is 400 meters long, then 3 laps will have a total distance of 400*3 = <<400*3=1200>>1200 meters
The total time he ran was 70 on the first lap + 85 on the second one and 85 on the third lap, so his total running time was = 70+85+85 = <<70+85+85=240>>240 seconds
His average speed then is measured by the total distance he ran (1200) divided by the total time required (240) or 1200/240 = <<1200/240=5>>5 m/s
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