Question:
If the mean of 6, 7, x, 8, y, 14 is 9, then
(a) x + y = 21
(b) x + y = 19
(c) x − y = 19
(d) x − y = 21
Solution:
The given observations are 6, 7, x, 8, y, 14.
Mean = 9 (Given)
$\Rightarrow \frac{6+7+x+8+y+14}{6}=9$
$\Rightarrow 35+x+y=54$
$\Rightarrow x+y=54-35=19$
Hence, the correct option is (b).