questions:

1. why does water reach its maximum density at 4 degrees centigrade, in sharp contrast to many other liquids?

2. why are 1.06 males born for every female?

3. Chinese families place a hgh value on sons, yet the Chinese government exerts extreme pressure to limit family size. Let's assume that the chance of having a girl is exactly 50%, but every couple stops having babies once
they have a son. So some families have one son, some have one older daughter and one son, and some two older daughters and one son and so on. In this scenario, what percentage of chinese babies will be male?