What is a probability that when a couple has three children at least one of them is a boy?

There are two problems in answering this question. The gender of children are not independent events and also, the probability of a boy is not half as is often assumed but nearer to 52% and it varies over time and between countries.

However, if you assume that the genders are independent and that the probability of either gender is 0.5 then the answer is 0.875