Question:
If the arithmetic mean, 7, 8, x, 11, 14 is x, then x =
(a) 9
(b) 9.5
(c) 10
(d) 10.5
Solution:
The given observations are 7, 8, x, 11, 14.
Mean = x (Given)
Now,
Mean $=\frac{7+8+x+11+14}{5}$
$\Rightarrow x=\frac{40+x}{5}$
$\Rightarrow 5 x=40+x$
$\Rightarrow 4 x=40$
$\Rightarrow x=10$
Hence, the correct option is (c).