Multiple choice

The average of 30 results is 20 and that of other 20 results is 30. What is the average of all the results?

  1. 23

  2. 24

  3. 28

  4. 15

  5. 14
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B Correct answer
Explanation

Total sum = (30 * 20) + (20 * 30) = 600 + 600 = 1200. Total number of results = 30 + 20 = 50. Average = 1200 / 50 = 24.

AI explanation

Using the weighted average method, the sum of the first 30 results is 30 times 20, which is 600, and the sum of the other 20 results is 20 times 30, which is 600. The total sum of all 50 results is 600 plus 600, giving 1200. The overall average is 1200 divided by 50, which equals 24.

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