Solve the classical probability problem

Don't put it back. 2. Get it for the third time? Not the second question.

Then analyze it

Solution 1:? Suppose there are 10 lottery tickets, 3 winning and 7 not winning. If you have 9 buddies, you count as 10, and you take the third place. What do you think are your chances of winning the lottery? Is it 3/ 10? Honey?

Ha ha, further extension, you are not the third person, but anyone, such as the last person. So, if the person in front doesn't watch the lottery, is the winning probability 3/ 10? Yes ~ obviously ~! So, does it matter whether the first nine people watch the lottery or not? Obviously not, so this classical probability is very reasonable, so the World Cup final is also decided by lottery, isn't it?

If you can't understand the above? look underneath

Solution 2: the probability of drawing the third card = the probability of drawing one of the first three cards (drawing the third card)+the probability of drawing two of the first three cards (drawing the first or second card, drawing the third card)+the first three cards are all drawn.

Right? Do the math yourself, and you will be surprised to find that the result is equal to 3/ 10? If not, you can Baidu hi me.

I hope LZ will go further.