Multiple choice

If the arithmetic mean of 7 observations is 100 and that of 3 observations is 50, then the combined arithmetic mean would be

  1. 75

  2. 85

  3. 100

  4. 65
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B Correct answer
Explanation

The combined mean is calculated by finding the total sum of all observations and dividing by the total number of observations. Total sum = (7 * 100) + (3 * 50) = 700 + 150 = 850. Total observations = 7 + 3 = 10. Combined mean = 850 / 10 = 85.

AI explanation

We calculate the total sum of the first group as 7 multiplied by 100 to get 700, and the total sum of the second group as 3 multiplied by 50 to get 150. The combined arithmetic mean is the total sum of all observations divided by the total number of observations. Therefore, the combined mean is (700 + 150) divided by 10, which equals 850 divided by 10, resulting in 85.

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