Actually, while it's got a probability of 7.46 * 10^-9, that doesn't effect it's chance (as the most basic level) which is ALWAYS 50/50. Just because you flip a coin 40 times, doesn't mean it won't always land heads. It gets less and less probable, but the chance always remains the same.
Each time a kid is born, it has a 50% chance of being a boy or a girl.
have to agree with leo here. the words are used differently; probability always means an amount of possibility, while the word chance may refer simply to the existence of a possibility. However, once you describe a Percentage of chance, or how much chance, or 'the odds' or that someone has one chance in 10 or 100... you are using the definition of chance which is identical to the definition of probability.
example:
"Each time a kid is born, it has a chance of being a boy or a girl."
chance used meaning possibility.
"Each time a kid is born, it has a probability of being a boy or a girl."
this sentence is incorrect; as you can see, probability cannot be used the same way as the word chance, it cannot just mean possibility. But, if you ascribe an Amount of chance...
"Each time a kid is born, it has a 50% chance of being a boy or a girl."
"Each time a kid is born, it has a 50% probability of being a boy or a girl."
the terms become interchangeable here.
you seem to say that degrees of chance simply describe how many possible outcomes there are; if there are 2 outcomes there is always 50/50 chance. But if you flip a coin 2 times, there are 4 possible outcomes (sequences of heads and tails: heads heads, heads tails, tails heads, tails tails).... if you flip it 3 times, there are 8 possible outcomes... percent-chance and probability do not scale differently. they only appear to do so when someone says 'what is the chance that x,' because this quantifies the situation to a single instance instead of a sequence of incidences. "What is the chance I'll eventually get heads if I flip a coin 50 times?" the same as the probability; 50%. "What is the chance that I'll get heads the first time?" 50% chance or probability. "What is the chance I'll get heads 25 times out of 50?" much different; maybe 1 in 50. "What is the chance I'll get heads 25 times -in a row-?" again, much different. But still, the chance is the same as the probability.... and the same as the odds, or the likelihood, etc.
TLDR the word 'chance' has many definitions, but one of those definitions is identical to probability.