Question

If the arithmetic mean of x, x + 3, x + 6, x + 9, and x + 12 is 10, the x =

(a) 1
(b) 2
(c) 6
(d) 4

Answer 1

The given observations are x, x + 3, x + 6, x + 9, and x + 12.

$\therefore \sum _{}x=5x+30,n=5,\overline{X}=10$

Now,

Hence, the correct option is (d).