The learning of probability is like this. Probability is actually the continuous learning of permutation and combination and the practical application of permutation and combination. If you want to learn probability well, you should work hard on permutation and combination now. Anyone who has studied probability knows how to calculate it. Is it "special case" divided by "general case"? The general situation is generally a complete arrangement, and sometimes some situations need to be excluded from the general situation, which is relatively simple. The key is that the above molecules, that is, "special cases", need your knowledge of permutation and combination.

How many situations exist in the calculation of permutation and combination? Generally, it is necessary to find out the essence of the problem and see what you want, and then you will start thinking in your mind, whether to do it step by step, or to classify it first and then do it step by step, and pay attention to the special limitations of the topic. Don't start making random calculations as soon as you have an idea in your mind. The starting time is limited, so you must think it over before calculating.

Probability is relatively difficult, but if you learn well, the distribution list at the back will be a piece of cake. Please, I wrote the words on it myself!