Multiple choice

The algebric sum of deviations of $10$ observations measured from $15$ is $7$. The mean is

  1. $105$
  2. $70$
  3. $15.7$

  4. none of these
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C Correct answer
Explanation

The sum of deviations from 15 is 7, so the sum of the observations is 10 × 15 + 7 = 157. Dividing by 10 gives a mean of 15.7.

AI explanation

The algebraic sum of deviations from a value is calculated as the number of observations multiplied by the difference between the actual mean and that value. This gives 10 times (mean - 15) = 7. Solving this equation yields mean - 15 = 0.7, so the mean is 15.7. The result is 15.7.

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