How deep does the sperm have to be in order to fertilize an egg?
the sperm travels to the tubes where they will wait on the egg. once meeting the egg, they will travel together back down and implant.
Sperm have tails so it does not matter how deep it is. They swim up to the egg by themselves
What determines that the sperm with the x chromosome or the sperm with the y chromosome will fertilize the egg?
No, and yes. A zygote is the product of one egg and one sperm, so in this sense only one sperm will fertilize the egg and so only one man will be the father. However it's worth noting that it takes multiple sperm to get through the surface of the egg in order for that one final sperm to fertilize the egg - basically it takes multiple sperm to fertilize the egg, which may include…
If you are asking "how long does it take for the sperm to fertilize the egg once it penetrates the egg wall?", it is instantaneous. That's what "fertilized" means. If you are asking "how long does it take the sperm to fertilize the egg once it enters the female body?", there is no exact answer. it could take from a few minutes to a few days.
it is important for 1 sprem to fertilize a human egg (Ova) in order to start the conception process. If 2 sprem Cells fertilize the 2 DIFFERENT Ova the mother will have "Fraternal Twins". However, if 2 sperm cells fertilize the SAME Ova (egg) the mother will have "Identical Twins". I hope that is the answer you were looking for?