Hume "probability"

I was reading Hume's section on Probability and I found it interesting how it relates to everyday life. If there are 8 cards that consist of the follow: 4 -Aces, 2 -Kings, 1- Queen, and 1- Jack, the probability of you picking one of the Aces is a very good chance because there are more of that kind of card than the rest. This goes for many things in life. One example that Hume used was that in Europe all of the countries in January have frost on the ground. This is true because of the weather. But lets consider this thing called "global Warming".. one of the days may be warmer and there may be no frost. This makes the outcome for frost less probable than before but it still is more likely to occur than the no frost days. Some things in life as Hume says we can tell what the cause and effect are going to be such as a fire, it will light up and will burn, but there are other things that we can not make a call on. For example, drugs effect people differently. Some make do nothing for one person while the other person is hallucinating and breaking out in a sweat. You can never tell how something like drugs will effect someone. "We transfer the past to the future, in order to determine the effect, which will result from any cause, we transfer all the different events, in the same proportion as they have appeared in the past, and conceive one to have existed a hundred time, for instance, another ten times, and another once. As a great number of views do here concur in one event, they fortify and confirm it to the imaginations... which we call belief..."