Multiple choice

Willow went up to the top of a mountain using a motorbike on an elevated road at an average speed of 60 miles per hour. She used the same path for the return journey and, to be safe and secure, she didn't speed up much, and traveled at an average speed of 40 miles per hour. If she covered the whole distance in 2 hours without any stops, how long was the one-way path?

  1. 48 miles

  2. 50 miles

  3. 52 miles

  4. 54 miles

  5. 65 miles
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A Correct answer
Explanation

Let d be the one-way distance. Time up = d/60, time down = d/40. Total time = d/60 + d/40 = 2. (2d + 3d) / 120 = 2, so 5d = 240, d = 48 miles.

AI explanation

Use the formula for average speed when distances are equal, which is twice the product of the speeds divided by their sum. The average speed is 2 multiplied by 60 multiplied by 40, divided by 100, resulting in 48 miles per hour. The total distance for the round trip is this average speed multiplied by the total time of 2 hours, giving 96 miles. The one-way distance is half of the total distance, which is 48 miles.

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