We can't separate the possible events from the possible events, Haizhou Haina company must pack five first-class products into a box when exporting a kind of parts. A worker mistakenly put two first-class products into a box when operating. Now he must inspect the second-class products and reload them into the first-class products. 1 if two first-class products are sampled each time, write down all the basic events 2 take two pieces at a time and find the probability of at least one second-class product (1) Two first-class products, one first-class product, one second-class product, two second-class products (2) C (2,1) C (3,1) + C (2,2)} / C (5,2) = 7 / 10, which means that it is possible to take one and another from two equal, and then add the possibility of taking all two equal, and divide by the total number of two equal. That's the probability of this problem, right? But why is it an equal possible event But the probability is 2 / 3, isn't it? Pick out two pieces that are either second-class or first-class Why not wait for a possible event

We can't separate the possible events from the possible events, Haizhou Haina company must pack five first-class products into a box when exporting a kind of parts. A worker mistakenly put two first-class products into a box when operating. Now he must inspect the second-class products and reload them into the first-class products. 1 if two first-class products are sampled each time, write down all the basic events 2 take two pieces at a time and find the probability of at least one second-class product (1) Two first-class products, one first-class product, one second-class product, two second-class products (2) C (2,1) C (3,1) + C (2,2)} / C (5,2) = 7 / 10, which means that it is possible to take one and another from two equal, and then add the possibility of taking all two equal, and divide by the total number of two equal. That's the probability of this problem, right? But why is it an equal possible event But the probability is 2 / 3, isn't it? Pick out two pieces that are either second-class or first-class Why not wait for a possible event

There are three situations: one or two are first-class products, the probability is 2 / 5 * 1 / 4 = 1 / 10, the first-class product, the second-class product, the probability is 3 / 5 * 2 / 4 = 3 / 10, the first-class product, the second-class product, the probability is 2 / 5 * 3 / 4 = 3 / 10 If you want to ask about an equal probability event, I can say that you still have the same probability of positive and negative sides of a coin. This is an equal probability event. But you can take any one from a box of products just now, It means that the proportion of two or more events to the total events is different