The empirical rule is a rule-of-thumb guide to evaluating percentages associated with z-scores, for normal distribution.
|z|=1, 68%; |z|=2, 95%; |z|=3, 99%.
For the given numbers the z-scores are:
150: (150-166)/8=-2
182: (182-166)/8=2
142: (142-166)/8=-3
190: (190-166)/8=3
So for 150 and 182 the empirical rule the percentage is 95%; for 142 and 190 it's 99%.