Find out all the basic events included in the random test and the number of basic events included in the request event; Find out what probability model it is and which formula to apply; 3. Remember the formulas of mean, variance and standard deviation;
When calculating the probability, the frontal difficulty is opposite (according to p1+P2+...+PN =1); Pay attention to basic methods such as enumeration and tree diagram when counting; Pay attention to put back the sample, not put back the sample;
Pay attention to the penetration of "scattered" knowledge points (stem leaf diagram, frequency distribution histogram, stratified sampling, etc.). ) in the big question; Pay attention to conditional probability formula; Pay attention to the problem of average grouping and incomplete average grouping.
The object of middle school mathematics research can be divided into two parts, one is number, the other is shape, but there is a connection between number and shape, which is called combination of number and shape or combination of shape and number. It is not only a "magic weapon" to find the breakthrough point of solving problems, but also a "good prescription" to optimize the way of solving problems. Therefore, it is suggested that students draw as many pictures as possible when solving math problems, which will help to understand the meaning of the problems correctly and solve them quickly.