Three observations of a random sample of size 5 are 12, 6, 15. If sample mean is 10 and difference between 2 missing observations is 1, the two missing observations are :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 8, 9
Let the missing observation be x and y.
$x-y=1$ ....(1)
$\text{Mean} = \frac{\text{Sum of all observations}}{\text{Sample size}}$
$⇒10=\frac{12+6+15+x+y}{5}$
$⇒x+y=17$ ...(2)
Add (1) and (2)
$2x=18$
$x=9$ and $y=8$