WAEC 2020 · Paper 2 · Q6

Using an assumed mean of $14$ , calculate the mean of $43, 12, 19, 14, 35, 22, 13, 16$ and $26$ .

Worked solution (try it first)

With an assumed mean $A = 14$ , work with the deviations $d = x - 14$ instead of the numbers themselves.
Set them out in a table:
$x$ 43 12 19 14 35 22 13 16 26

$d = x - 14$ 29 $-2$ 5 0 21 8 $-1$ 2 12
$\sum d = 29 - 2 + 5 + 0 + 21 + 8 - 1 + 2 + 12$
$= 74$ , and $n = 9$ .
Mean $= A + \frac{\sum d}{n}$
$= 14 + \frac{74}{9}$
$= 14 + 8.2222$
$= 22.2222$ (to 4 d.p.).

$x$	43	12	19	14	35	22	13	16	26
$d = x - 14$	29	$-2$	5	0	21	8	$-1$	2	12