You can put this solution on YOUR website! How long does it take to go 20' while traveling 1.5 mph? How about at 2 mph?
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15 mi/hr = 22 ft/sec (I remember that, you can figure it out if needed)
--> 1.5 mi/hr = 2.2 ft/sec
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d = r*t
t = d/r = 20 ft/2.2 ft/sec
t =~ 9.091 seconds
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2 mi/hr is 4/3 as fast --> 3/4 the time
t =~ 6.82 seconds
