The mean of 5 observations is 5 and their variance is 12.4. If three of the observations are 1, 2 & 6; then the value of the remaining two is :

JEE Main 2016 Mathematics question

The mean of 5 observations is 5 and their variance is . If three of the observations are 1, 2 & 6; then the value of the remaining two is :

Answer: (3)

From the mean, , so the two unknown observations sum to . From the variance,

- = 12.4 ⇒ = 5(12.4+25) = 187.

The three known values contribute $1+4

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Question ID VK-115659