Hi
Population of City | NE | SE | SW | NW
... < 10,000 | 7% | 6% | 3% | 0%
.10,000 to 100,000 | 15%| 3% | 12%| 5%
.... > 100,000 | 20%| 4% | 1% | 24%
total 42% 13%
P(>=10,000 |Eastern) | reads "Given"
P(A|B) = P(A and B)/P(B)
P(>=10,000 |Eastern) = P(>=10000 and Eastern)/P(Eastern) == 42/55 = .764