Multiple choice

An athlete runs $300$ metres up a hill at a steady speed of $3.0$ m/s. She then immediately runs the same distance down the hill at a steady speed of $6.0$ m/s. What is her average speed for the $600$ metre run?

  1. $2.0$ m/s
  2. $3.0$ m/s
  3. $4.0$ m/s
  4. $4.5$ m/s
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Average speed = Total distance / Total time. Total distance = 600 m. Time up = 300 / 3 = 100 s. Time down = 300 / 6 = 50 s. Total time = 150 s. Average speed = 600 / 150 = 4.0 m/s.

AI explanation

Using the average speed formula for equal distances, 2xy divided by (x+y), where x and y are the two speeds, we calculate 2 multiplied by 3 multiplied by 6, and divide by the sum of 3 and 6. This gives 36 divided by 9, which results in an average speed of 4.0 m/s.

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