Multiple choice

In a race among 10 participants, each runs a distance in kilometers which is twice the number of the position he occupies from the beginning of the row. What is the average distance (in kilometers) run by these 10 participants?

  1. 9

  2. 11

  3. 13

  4. 15
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B Correct answer
Explanation

Distances are 2*1, 2*2, ..., 2*10. Sum = 2 * (1 + 2 + ... + 10) = 2 * (10 * 11 / 2) = 110. Average = 110 / 10 = 11.

AI explanation

The participants run distances equal to twice their positions, meaning the distances are 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 kilometers. The sum of these distances is 110 kilometers. Divide this total by the 10 participants to find the average, which is 11 kilometers.

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