Answer: approximately 3.57 seconds
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Work Shown:
x = number of seconds
distance = speed*time
250 meters = (70 m/s)*(x seconds)
250 = 70x
70x = 250
x = 250/70
x = 3.57142857142858
x = 3.57
It takes approximately 3.57 seconds for the car to travel 250 meters, when it travels a constant speed of 70 meters per second.