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 = 
<gadget id="calculator">400*3</gadget>
<output>1_200</output>
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 = 
<gadget id="calculator">70+85+85</gadget>
<output>240</output>
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 = 
<gadget id="calculator">1200/240</gadget>
<output>5</output>
5 m/s.

<result>5</result>