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In an experiment with 15 observations on x , the following results were available: x^2=2830, x=170 One observation that was 20 was found to be wrong and was replaced by the correct value 30 . The corrected variance is

Options

  1. A8.33
  2. B78.00
  3. C188.66
  4. D177.33

Correct answer

B. 78.00

Step-by-step solution

x=170, x^2=2830 increase in x=10 , then x^ =170+10=180 Increase in x ^2=900-400=500 then x^ 2 =2830+500=3330 Variance = 1 n x^ 2 - ( 1 n x^ )^2= 1 15 3330- ( 1 15 180 )^2=222-144=78

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