Yeah, by definition, half of the population has below-average intelligence ...
Actually, by definition half of the population is below the *median*, not the average/mean. If the distribution is pretty even on both sides, the two will be close. If, say, most of the individuals above the median are just a little above it, but most of the induhviduals below the median are way, way below it, the average/mean will be significantly lower than the median.
Alternately, let's say there's a neighborhood with 10 houses. One is valued at $1 million, five at $100k, and four at $200k. The median would be $150k, but the average would be $230k.
