(2/3a • 9a) + (2/3 • 6) = 23.8
a = 2.1259 or 287/135
There follows the formula for "z-score:"
raw score - mean
z = ------------------------------
standard dev
9.1 - 8
Here, the z-score is z = ------------- = 0.344
3.2
<span>5 x 9
9 (3 x 3)
5 x 3 x 3 = 45</span>