Professor Yu's hint is obvious, and this marriage proposal question will most likely appear on tomorrow's math paper.

The topic hinted at by the professor must be a very important topic, and the importance is worth studying all night and finding the real mystery hidden in it.

Xia Lu's dinner is solved in the canteen, white rice, big steamed buns, braised pork, boiled eggs, a plate of green vegetables, meat and vegetarian combinations, balanced nutrition, large amounts of full.

While eating, Xia Lu kept thinking, why is it the second girl?

What mathematical theories are needed to derive this result?

Tomorrow's math final exam paper will most likely have the following question: "Suppose a man with a marriage plan meets 7 girls in the next 7 years...... How many girls did he propose to the most successfully, and why?"

The most critical question is the "why", i.e. the second girl as the theoretical support for the correct answer.

"This question is beyond the scope of my mathematical knowledge......

Xia Lu pondered for a long time, why set 7 years and 7 girls, why is the second sister the most suitable person to get married?

2 divided by 7 equals 0.286.

Why 0.286 and not 0.618?

What mathematical theory does 0.286 imply?

Why, exactly, and why?

Wait a minute!

Professor Yu just said something inadvertently.

"Let her pass the past, but the past still retains mathematical significance. ”

That's right, that's it!

Review Professor Yu's question again: "Suppose Xia Lu has talked about a girlfriend before, and you will date 7 girls in the next 7 years......"

"Ah, I see!"

Xia Lu suddenly realized, because he was too excited, he actually crushed the egg.

The past still retains its mathematical significance!

The first hypothetical ex-girlfriend must be considered.

So the denominator is not 7, but 8!

Therefore, the second of the 7 girls is the third of the 8 girls!

3 divided by 8 equals 0.375.

0.375 doesn't have any mathematical significance, at least in the mathematical knowledge that Xia Lu currently has, he doesn't think 0.375 is a very hanging number.

However, 0.368, which is close to 0.375, has strict mathematical significance.

"Interesting, really interesting!"

Xia Lu quickly disposed of the remaining food and went to the library.

0.368 is a little more than a third, and Xia Lu thought of Bayes' theorem.

That's right, Bayes' theorem.

According to Bayes' theorem, out of the 8 girls you date, the one who is "a little more than a third" is the most likely to be your bride.

3 divided by 8 is the closest result to 0.368, so the third of the 8 girls is the correct answer.

The above speculation comes from Xia Lu's unilateral conception, and his understanding of Bayes' theorem and the entire probability system is still at a relatively shallow stage.

Professor Yu Feng is nominally the teacher of advanced mathematics for first-year students in the science experimental class of Hongyi Academy, but some of his teaching content has gone beyond the advanced mathematics syllabus.

Of course, the experimental class is different from the ordinary class, and it is normal to exceed the curriculum.

Xia Lu had the impression that at a teacher-student tea party with Professor Yu earlier this month, Professor Yu talked about Bayes' theorem.

Professor Yu seemed to say at the time: "When you are faced with many options, for example, there are 1,000 options, and you can only do multiple choice questions, then don't make a choice before 0.368 of the total number of options, that is, before the 368th option...... Bayes' theorem is an interesting theory, and I'll explain it to you in detail when I have time. ”

As the month draws to a close, Professor Yu did not explain Bayes' theorem in detail, but he threw out this concept and left it to those who are interested in studying it.

Xia Lu typed the "Bayesian theorem" into the library's electronic system and then searched the literature.

Hundreds of useful pieces of information were swiped out.

Many mathematical monographs and papers contain Bayes' theorem, and there are more economic literature than mathematical literature.

Xia Lu borrowed a bunch of literature, both mathematics and economics.

After some study, Xia Lu got the core idea of Bayes' theorem: to use the known experience of the past to speculate the probability of a certain event in the future.

Bayes' theorem 0.368 cut-off point is written in the academic literature, but if the total number is not known, 0.368 will lose its meaning.

Going back to the marriage proposal question, 8 marriage proposals are the number that Professor Yu hypothesizes.

It is unknown how many girls or boys a person will meet in this life.

It is also unknown how many options we will be faced with in our lifetime.

How to derive and calculate the unknown probability, and how to do it?

This is very complicated, requiring extremely deep mathematical skills and extraordinary brains, which may be a problem considered by a mathematical expert like Professor Yu.

Xia Lu, a freshman with only one star of elite brain power, felt so humble and small in the vast ocean of knowledge.

If you are stupid, you should read more.

Obsessed with books, Xia Lu travels through time and space to communicate ideas with historical players such as Bayes, Bernoulli, Fermat, Nash, and Pareto.

It doesn't matter which girl you propose to.

Math final exams aren't that important anymore.

It's the knowledge that matters.

A tribute to knowledge.

Mathematical knowledge valuation +102

Valuation of knowledge of economics +66

Valuation of English knowledge +18

(Some of the documents borrowed by Xia Lu are in English)

Because he had a full dinner, was young and in good health, and more importantly, his mental pleasure diluted his physical exhaustion, and before he knew it, Xia Lu soaked in the library all night.

"It's 7 o'clock, oh, it's time for breakfast. Xia Lu left the library and prepared to go to breakfast.

Just a few steps out of the library door, Xia Lu heard someone behind him shouting his name.

Xia Lu glanced back, and the person behind him was Zhang Kai.

Zhang Kai's eyes were red, and it was estimated that he had also spent the night in the library.

"Let's go Zhang Kai, let's go to the cafeteria for breakfast. Xia Lu said, and the two walked together.

"It's been a long time since I've been studying all night, and my body can't bear it. Zhang Kai's face was tired, and he said: "Fortunately, the math test is scheduled for four o'clock this afternoon, and I can go back to the dormitory to sleep for a few hours after breakfast." Xia Lu, do you have a delusion, how can you be more tired in college than in the third year of high school?"

Xia Lu nodded and said, "Yes, but there is no way, everyone works so hard, if we don't advance, we will retreat, we can only rush forward." ”

Zhang Kai asked, "Have you comprehended Professor Yu's marriage proposal?"

Xia Lu: "It can't be regarded as a complete comprehension, it can only be said to be a small experience." ”

"Oh, tell me what you learned. Zhang Kai made an open mind to ask for advice.

"Huh. Xia Lu smiled and said, "Zhang Kai, your math level is the highest in the class, and the harvest must be greater than mine, you say it first." ”

"Xia Lu, Xia Lu, am I a thief? You actually guard me like this?" Zhang Kai was very sad, he said extremely melancholy: "I was going to the bright moon, but the bright moon shines on the ditch." It's just a Bayesian theorem, why do you have to do that?"