2. If you spend 160 yuan to buy 20 yuan's profits (if you don't win, you will get a bonus of 180), it can be understood as follows: if you buy 10 issues in succession, each time you spend 160 yuan, you will get/kloc in eight times according to the winning probability of 80%. The other two misses, loss 160*2=320 yuan; In this way, according to the mathematical probability, we will lose 10/60 yuan. Such a formula is in the interest of bankers.
According to you, this lottery ticket should be for 2 yuan and 9 yuan with a probability of 10%. Many small games are similar to this award formula. For example, in 3d, every time 2 yuan wins 1 1,000 yuan, the probability is 0. 1%, and the total package is 2,000 yuan.
4. Hit 20 yuan's profits with 160 yuan. Although this method has many packages and high winning rate, the cost is too high relative to the income. If you keep playing, you will lose money. You can refer to 3d and permutation 3 in gameplay, but this gameplay is really unattractive.