Multiple choice

If the mean of group A of 10 observations is 18, and that of group B of 12 observations is 23, then what will be the combined mean of the two groups?

  1. 20.73

  2. 1.87

  3. 20.27

  4. 2.86
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A Correct answer
Explanation

The combined mean is calculated as (n1 * mean1 + n2 * mean2) / (n1 + n2). Plugging in the values: (10 * 18 + 12 * 23) / (10 + 12) = (180 + 276) / 22 = 456 / 22 = 20.7272..., which rounds to 20.73.

AI explanation

The combined mean is calculated by dividing the total sum of all observations by the total number of observations. The sum of group A is 10 times 18, which is 180, and the sum of group B is 12 times 23, which is 276. The combined mean is the total sum of 456 divided by the total count of 22, resulting in 20.73.

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