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Paragraph : The mean and standard deviation of 100 items are 50, 5 and that of 150 items are 40, 6 respectively. Question : What is the variance of all the 250 items?

Options

  1. A50.6
  2. B53.3
  3. C55.6
  4. D59.3

Correct answer

C. 55.6

Step-by-step solution

aligned & Required variance & = 100[25+36]+150(36+16) 250 & = 6100+7800 250 = 1390 25 =55.6 . aligned

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