The mathematical probability of the third grade can be preliminarily found that when coins are repeatedly thrown,
If you toss a coin 20 times, the probability of heads is 0.4, that is, 0.5-0. 1, then if you toss a coin 20 times, the probability may be 0.5+0. 1, which will reach 0.5 on average. Although it is a little simple to say this, it is still understandable. Therefore, the more times you flip it.