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A runner ran two laps around a 400m track.She completed the first lap in 50 seconds and then decreased her speed by 5% for the second lap.Find:

a)her speed on the first lap
b)her speed on the second lap
c)her total time for the two laps
d)her average speed for the two laps

(a) 400m/50s = 8 m/s

(b) 8 * 0.95 = 7.6 m/s
(c) (400/8 + 400/7.6) = 102.63 s
(d) 800m/102.63s = 7.79 m/s

Did you know?

Did you know that when a runner decreases their speed by a certain percentage, it can affect their overall time and average speed? In this example, the runner completed the first lap of a 400m track in 50 seconds. For the second lap, she decreased her speed by 5%. To find her speed on the first lap, we can simply divide the distance (400m) by the time it took (50 seconds), resulting in a speed of 8m/s. To find her speed on the second lap, we take 95% of her original speed, or 8m/s × 0.95 = 7.6 m/s. To calculate her total time for the two laps, we add the time for the first lap (50 seconds) to the time for the second lap. Finally, the average speed for the two laps can be found by dividing the total distance (800m) by the total time taken.