The first thing Chen Bo did when he returned to the dormitory was to hurry up and complete his homework after class.

The afternoon class is "Probability Theory", which is different from the regular one, and its main focus is on metaphysical gacha.

"How long does it take to finish the question?" Chen Bo had never been exposed to the relevant content, and planned to turn over the textbook first.

Wang Xu roughly estimated: "About half an hour." ”

Chen Bo glanced at the computer desktop bar, there are still nearly two hours before 0:00 in the morning, and there is more than enough time to preview and then strike while the iron is hot.

Gacha has a long history, it evolved from Nintendo's gacha system, and almost with the development of smartphones and social networks, the earliest gacha games can be traced back to 2010 SE's "Crystal Knight".

What really brought the card drawing function into the field of vision of domestic players was undoubtedly the "Onmyoji" launched by the pig factory, which created a famous saying that was widely circulated at that time - Xuan does not save the wrong, Krypton does not change his life, the world is European, and you are the only one.

After that, no matter what type of game, there will always be a gacha gimmick added to the gameplay, card development unlocks new characters through card drawing, and role-playing opens new props through card drawing.

The game is free, but if you want to play it, hehe, please open your money bag and be a man.

Returning to the essence of card drawing, in fact, it is no different from gambling, a rare item of equipment, if the price is clearly marked, the vast majority of players will definitely not be blessed.

It is difficult for them to pay a few thousand yuan at a time, but they can pay 5 yuan and 10 yuan at a time, and with the accumulation of times, the final income is amazing.

The textbook also cites actual cases, this is a little-known game factory, on the day of the opening of the service, the price of the version of the top weapon was listed in the mall, and the price of 5000 yuan discouraged many people, and less than 100 people started in three days.

The game planning urgently adjusted the form of sale, removed the weapon from the mall, transferred to the gacha system, the probability is set to 0.5%, each draw costs 10 yuan, ignoring the impact of the first charge benefit, from the perspective of expected value calculation, 2000 yuan can be owned.

Despite being scolded for being ugly, the data in the background honestly exposed the players' behavior, and in just one day, the revenue generated by the gacha was 7.5 times that of the original model.

After introducing the advantages of gacha, the textbook officially entered the category of probability theory.

At first, the card draw was just a simple probability random, for example, 1%, not 100 times must be 1 time, there will always be a few unlucky eggs and a few 100 times something was not drawn, and the lottery experience between players is huge.

Assuming that a game has 100,000 active users and a deviation rate of 5%, at least 5,000 non-chieftains spend money and can't draw what they want.

Chen Bo was stunned, he was looking at Xing, and suddenly popped up the question.

[Assuming that the probability of winning is 10%, please calculate the probability of not winning 10 times, 100 times and 5 times]

The problem is a basic mathematical expectation calculation, and the formula is 0.9 to the tenth power, and about 34.9% of people are not successful.

In the same way, 100 draws are 0.9 to the 100th power, rounded to the 3/100,000, and 5 draws are 0.1 to the 5th power, 1 in 100,000.

"It's really shipped randomly according to the probability, and the proportion of non-chiefs is obviously more than that of the European Emperor, no wonder players are complaining." Chen Bo suddenly realized.

In order to solve this problem, the developers have spent a lot of effort on the card drawing mechanism, and the most crude is the fixed guarantee, the money is in place, everything will be exploded for you, rest assured and bold krypton.

Of course, there are drawbacks to the fixed guarantee, not all players can reach that level of consumption, not much money, black faces, and greedy players are still widespread, and the planner has to add a level ladder on the basis of the quota guarantee, reaching a certain level, and automatically triggering the guarantee of the corresponding card pool.

In this way, players can feel the pleasure very comfortably when drawing cards: "Hey, Lao Tzu spent so much money, and finally shipped it, keep up the good work, and strive to win the SSR." ”

Giving you a little hope when you are desperate, and plunging you into despair again when you see hope, this is how players' wallets are emptied, many people are born gamblers, do not believe in fate, and always fantasize that the next shot will come out, and as a result, 648 is charged into the water and does not make a splash.

In addition to the fixed guarantee, the probability increase method used in Blizzard games is also a common form in the gacha mechanism, assuming that the orange loading rate is 10%, the initial gacha probability is much lower than 10%, and with the increase of the number of times, the probability of winning the next lottery will also increase, until it returns to the original point after winning.

Compared with the first two, Chen Bo prefers the fixed amount guarantee, the good guy is a double halo of normal probability + non-chief comfort, and the probability increase method makes it clear that if you don't give a way to live, you have to charge more money if you want to ship.

[Please determine which of the following metaphysical behaviors does not change the winning rate]

"Really, please don't insert questions in the textbook." Chen Bo dragged the electronic draft book that he had prepared to the side and was eager to try.

["Good Luck Comes" and "The Emperor of Europe" are played on a loop when the card is drawn]

Chen Bo gave the mistake without thinking, the content introduces a probability model, and it has nothing to do with what song is played.

[Gacha at a specific time and place]

Chen Bo hesitated for a moment, and still gave the wrong one, the question did not say whether the next one is a guaranteed card, from the perspective of probability, most of the cases of normal face black.

[I didn't win ten consecutive draws, so I changed my friends to draw]

This question is more confusing, Chen Bo regards his friends and himself as independent individuals, and the probability of both of them having a black face and ten empty bags is 34.9%, which will not be improved because of the change of person.

[The old number has a black face, and the new number is kryptonite gacha card]

"Tut-tut, this seems a bit logical."

The life cycle of a mobile game is usually only 3-6 months, and with the change of version, it is inevitable that the original magic card orange outfit will be obsolete.

Chen Bo has played several games himself, and the routines are similar, stimulating consumption in the new area, so that the newcomers who enter the pit can catch up with the pace of the old area as soon as possible, and it is normal to deliberately increase the explosion rate.

He was right.

[Draw cards after the launch of the new card pool]

"Huh." Chen Bo has a deep understanding and ticks the box smoothly.

"Perfect, all right."

Seeing a green grassland, Chen Bo proudly cocked his legs, the effect of the nutrient solution was really strong, and the content he read was unforgettable, and he could even distinguish between the Microsoft Yahei and Song Ti used.

"Mr. Wang, do you have any supper?"

"No, you don't lose weight, you don't want the bonus."

"You're right, I'm going to keep my mouth shut." Chen Bo dispelled this thought.