Question

Thirty years ago, police would check a highway for speeders by sending a helicopter up in the air and observing the time it would take for a car to travel between two wide lines placed 1/10th of a mile apart. On one occasion, a car was observed to take 7.2 seconds to travel this distance.

What is the speed of this car in miles per hour?​

Answer 1

Answer: 50 mph

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Work Shown:

1/10 = 0.1

0.1 mile = 7.2 seconds

1 mile = 72 seconds (multiply both sides by 10)

1/72 mile = 1 second (divide both sides by 72)

3600/72 = 3600 seconds (multiply both sides by 3600)

50 miles = 3600 seconds

50 miles = 1 hour

The car's speed is 50 mph

Note: 1 hour = 60 min = 60*60 = 3600 seconds