Multiple choice

A truck covers a distance of 240 miles on its outbound journey at a speed of 120 miles per hour. For the return trip over the same route, its speed drops to 80 miles per hour due to congestion. What is the truck's overall average speed for the complete round trip?

  1. 82 miles per hour

  2. 84 miles per hour

  3. 88 miles per hour

  4. 96 miles per hour

  5. 98 miles per hour
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D Correct answer
Explanation

Average speed = Total distance / Total time. Total distance = 240 + 240 = 480 miles. Time out = 240 / 120 = 2 hours. Time back = 240 / 80 = 3 hours. Total time = 5 hours. Average speed = 480 / 5 = 96 mph.

AI explanation

Using the formula for average speed when distances are equal, the average speed is 2 multiplied by the product of the two speeds, divided by their sum, which is 2 multiplied by 120 multiplied by 80 divided by the quantity 120 plus 80. This simplifies to 19200 divided by 200, resulting in an overall average speed of 96 miles per hour.

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