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The mean of 7 observations is 10 and that of 3 observations is 5 . What is the mean of all the 10 observations?

Options

  1. A15
  2. B10
  3. C8.5
  4. D7.5

Correct answer

C. 8.5

Step-by-step solution

aligned Total of 7 observations & =7 10=70 Total of 3 observations & =3 5=15 Total of 10 observations & =70+15=85 Mean of 10 observations & = 85 10 =8.5 . aligned

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