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JEE Main 201610 AprilOnline
Exam
JEE Main
Year
2016
Date
10 April
Mode
Online
Subject
Mathematics
Chapter
Statistics

JEE Main 2016 · 10 April · Online · Mathematics · Statistics

The mean of 5 observations is 5 and their variance is 12 . 4 . If...

The mean of 55 observations is 55 and their variance is 12.412 . 4. If three of the observations are 1,2 and 61, 2 \text{ and } 6; then the value of the remaining two is :

Options

  1. A1,111, 11
  2. B5,55, 5
  3. C5,115, 11
  4. DNone of these

Correct answer

C. 5,115, 11

Step-by-step solution

\dfrac{x + y + 1 + 2 + 6}{5} = 5</p><p></p><p>⇒ x + y = 16</p><p>Now</p><p>Now12.4 = \dfrac{\left(16 + 9 + 1 + {\left(x - 5\right)}^{2} + {\left(y - 5\right)}^{2}\right)}{5}</p><p></p><p>⇒ 62= 26 + {\left(x - 5\right)}^{2} + {\left(y - 5\right)}^{2}</p><p></p><p>⇒ 36 = {\left(x - 5\right)}^{2} + {\left(y - 5\right)}^{2}</p><p>Shiftingoftheoriginto(5,5)</p><p>Shifting of the origin to \left(5, 5\right) the equations will become

62=x2+y2andx+y=6{6}^{2} = {x}^{2} + {y}^{2} and x + y = 6

Solving them and again will get the x=0ory=0x = 0 or y = 0.

If x=0⇒y=6x = 0 ⇒ y = 6 or

If y=0⇒x=6y = 0 ⇒ x = 6.

But by shifting the origin back to original position, we get x=0+5=5 and y=6+5=11x = 0 + 5 = 5 \text{ and } y = 6 + 5 = 11

(or)

x=6+5=11 and  x = 6 + 5 = 11 \text{\text{ and } } y = 0 + 5 = 5

Hence, the values of the remaining two are 5,115, 11.

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