More likely than not means that it is probable, i.e., the probability that some event happens is more than 50%.
Less likely means that it has more of a chance not to happen.
Maybe that he likes you ----more than likely so ---or it could also mean that he was just feeling playful ---but more than likely the first of the two
More than likely it is the initial for the manufacturer of the ring.
More than likely you are in close proximity to a railroad track!
You do not say what comparison you are making. You might mean, why are Australians more likely to get skin cancer than, let us say, the British are, or you might mean, why are Australians more likely to get skin cancer than they are to get liver cancer. Or you may want to know why they are more likely to get skin cancer than they used to be last year.
It means the dog is more likely to harm you than the lion which is dead.
It means that he likes you, most likely more than a friend ;)
she is more than likely cheating on you..SORRY
Your physical body will more than likely expire because of your illness.
Means he or she likes you more than likely.
It depends on what you mean. If you mean "more likely to fail chemistry and physics than to fail mathematics", then the answer is presumably yes. If you mean "more likely to fail chemistry and physics than some bozo who can't figure out how this 'multiplication' thing works", then no. In physics and (most kinds of) chemistry, a solid understanding of mathematics can only be helpful.