# The mean and vari

Given, Mean of 8 observation is 9 and variance is 9.25.

To Find: Find the other two observation

Assumption: Let x and y be the other two observation. And Mean is 9

Here, Mean = 60+x+y=72

X+y=12 ……(1)

Now, Let Variance (X) be the variance of this observation which is to be 9.25

If is the mean than we get,

9.25 = 9.25 = 642+x2+y2=722

X2+y2 =80 ---(2)

(x+y)2+(x-y)2=2(x2+y2)

By Subsititute the value we get,

122+(x-y)2=2×80

(x-y)2=160-144

(x-y)2=14

x-y =±4 ……(3)

On solving equations (1) and (3) we get,

X= 8, 4

And y = 4,8

Hence, The other two observations are 8 and 4.

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