How to calculate the probability? Mathematical method

The mathematical calculation method of probability is as follows:

1, direct counting method: if the number of possible events is small, we can directly calculate the number of occurrences of each event, and then divide the number of occurrences of each event by the total number of occurrences to get the probability of occurrence of the event. For example, when throwing a fair coin, the probability of heads up is 0.5, and the probability of tails up is also 0.5.

2. List test method: When there are many possible events, list test method can be used. List all possible events, calculate the number of occurrences of each event, and then divide the number of occurrences of each event by the total number of occurrences to get the probability of occurrence of the event. For example, if you throw a six-sided dice, the probability of each number appearing is 1/6.

3. Formula method: For some events, we can use formula method to calculate the probability. For example, if you roll a fair dice, the probability of each number appearing is 1/6. If thrown twice, the probability of the same number appearing twice is (1/6) 2 = 1/36, and the probability of the different number appearing twice is c (6 6,2) (1/6) 2 (5/6) 2 = 5/36.

Application of probability:

1, probability is widely used in weather forecast. Meteorologists use probability to predict the weather, such as the probability of rainfall, the probability of snowfall and so on. They use statistical methods and computer models to predict the weather, and compare the results with historical data to determine the most likely weather conditions. In addition, probability can also be used in meteorology to predict the occurrence probability of natural disasters such as earthquakes and typhoons.

2. Probability is also widely used in medical research. For example, in clinical trials, researchers use probability to calculate the effectiveness and safety of treatments and drugs. They can also use probability to predict the incidence of diseases, for example, according to the patient's age, gender, family history and other factors to predict the incidence of diseases.

3. In the financial investment field, the application of probability is also very important. Investors use probability to predict the price changes of stocks, bonds and other assets, as well as the trend of the whole market. They use statistical methods and computer models to analyze historical data and market dynamics and make investment decisions based on this information. In addition, probability can also be used to evaluate the balance between risk and return, and help investors make more informed investment decisions.