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BITSAT2022MathematicsStatisticsActual

The mean of five observations is 4 and their variance is 5.2 . If three of these observations are 1 , 2 and 6 , then the other two are

Options

  1. A2 and 9
  2. B3 and 8
  3. C4 and 7
  4. D5 and 6

Correct answer

C. 4 and 7

Step-by-step solution

Let the two unknown items be x and y . Then, Mean =4 1+2+6+x+y 5 =4 x+y=11 (i) and variance =5.2 1^2+2^2+6^2+x^2+y^2 5 -( mean )^2=5.2 41+x^2+y^2=5(5.2+16) array ll & 41+x^2+y^2=106 & x^2+y^2=65 array On solving Eqs. (i) and (ii), we get x=4, y=7 or x=7, y=4

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