

Given mean and variance of 7 observations are 8 and 16.
Five observations are 2, 4, 10, 12, 14.
Let the other two observations are x and y.
So 7 observations are : 2, 4, 10, 12, 14 ,x ,y
Now
Mean = (2+4+10+12+14+x+y)/7
=> 8 = (2+4+10+12+14+x+y)/7
=> 8*7 = 2+4+10+12+14+x+y
=> 56 = 42 + x+ y
=> x + y = 56-42
=> x + y = 14 ...................1
Again Given varience = 16
=> (1/7)*∑ (xi - mean)2 = 16 (7<=i<=1)
=> ∑ (xi - mean)2 = 16*7
=> ∑ (xi - mean)2 = 112
=> {(2-8)2 +(4-8)2 + (10-8)2 + (12-8)2 + (14-8)2 + (x-8)2 + (y-8)2 } = 112
=> {(-6)2 +(-4)2 + (2)2 + (4)2 + (6)2 + x2 + 64 - 16x + y2 + 64 -16y } = 112
=> {36 + 16 + 4 + 16 + 36 + x2 + y2 + 64 + 64 -16(x+y) } = 112
=> {108 + x2 + y2 + 128 -(16*14)} = 112 (since x+y =14)
=> {108 + x2 + y2 + 128 -224} = 112
=> x2 + y2 + 236 - 224 = 112
=> x2 + y2 + 12 = 112
=> x2 + y2 = 12-12
=> x2 + y2 = 100................2
Squaring equation 1, we get
(x+y)2 = 196
=> x2 + y2 + 2xy = 196
=> 100 + 2xy = 196
=> 2xy = 196-100
=>2xy = 96
=> xy = 96/2
=> xy = 48.............3
Now (x-y)2 = x2 + y2 - 2xy
= 100 - 2*48
= 100-96
= 4
=> x-y = √2
=> x-y = 2, -2
case 1: when x-y = 2 and x+y = 14
After solving it, we get x = 8, y= 6
case 2: when x-y = -2 and x+y = 14
After solving it, we get x = 6, y= 8
So the two numbers are 6 and 8
