In the first grade math problem, 9 out of 10 people made 9 mistakes, don t believe you try!

The problem from the beginning is to mislead people, first of all, let's determine how much money did the three of them spend in total? It was supposed to repay 50 yuan before 30 yuan, that is to say, the 3 of them spent 300-30 = 270 yuan, and the 20 yuan was not returned to the 3 of them, which means that the 20 yuan was included in the 270 yuan spent by the three of them, and the money spent plus the money spent (that is, 270 + 20) is meaningless, so it should be the money spent 270 plus the money not spent is the 30 yuan (270 + 30 = 300) returned!! I'm also using this question to play a lot of people, hehe!

It only cost 90 yuan per person, and 90 yuan per person for 3 people is 270 yuan 3 90 = 270 (yuan) plus the 20 yuan hidden by the waiter is 290 yuan 270 + 20 = 290 (yuan) "It's wrong here!" It should be that it only cost 90 yuan per person, 270 yuan for 3 people, and the 20 yuan hidden by the waiter is included in the 270 yuan, so it should not be added 20, but subtracted by 20. So 270-20 = 250 yuan is collected by the boss, 20 yuan is collected by the waiter, and 30 yuan is collected by the guest, a total of 250 + 20 + 30 = 300

How can I say that, if you think so.

Each person paid 90 90 * 3 = 270

The boss got 250 and the little two left 20

250+20=270 is also true.

The problem is to swap the concept Maybe you say 270 yuan, but what about the remaining 30?

30 in the hands of the three who lived in the inn.

Don't think about it according to 300, in fact, these people live in the hotel It took 270 to hope that the landlord thinks about it according to my method!

There are 10 yuan in 250 yuan! Not 90 per person, but 250 3 10 per person!

The 20 yuan for the waiter's collection should be subtracted, plus 50 yuan.

The answer should not be 15, it should be 3 people.

Reason: There are 25 10 15 people who only get the first question right, and 18 people who get the second question wrong, including 18 15 3 people who are only right about the first question and those who are completely wrong.

If you don't understand the answer, I suggest you make an equation, so that your thinking is simpler.

If there is a person in the class, then there are 25-10=15 people who only do the first way right, A-18-10 people who only do the second way right, and 10 people who do all the right.

Then there are a-(a-18-10)-15-10=3 people who don't do it right.

If there are only 10 people in the class who get it right, and 25 people get the first question right, then there should be 10 people who get the second question right, so that the class has and only 10 people get it right. If there are 18 people who get the second question wrong and 10 people who do it right, then there are 10 + 18 = 28 people in the class. Then there are 28-25=3 people who get the first question right.

If 18 people get it wrong in the second question, then there are 3 people who get it all wrong.

It should be the wrong answer.

The first question is answered by 25 people.

10 people who got it right.

Fifteen out of 25 got the second question wrong.

The second 18 people are wrong.

There were 3 people who got both questions wrong.

The answer is wrong.

There were only 10 people in the class who got all of them right, 25 people got the first question right, 15 people got the first question right, the second question got it wrong, 18 people got it wrong, and 3 people got it wrong.

Class size: 25+18=43

Number of people who have at least one question right: 25 + 25-10 = 40

Number of people who don't get any questions right: 43-40=3

2 25-10 40 (person) ......Get at least one question right.

40-25 15 (person) ......The first question is correct and the second question is wrong.

18-15 3 (person) ......I got both questions wrong.

After identification, the topic is not correct and cannot be done.

The number of people who get the first question right (25) = the number of people who only do the first question + the number of people who get both questions right (10), and the number of people who only do the first question is 15

The number of people who got the second question wrong (18) = the number of people who got the second question wrong (that is, the number of people who got the first question right only 15) + the number of people who got both questions wrong.

There are 18-15 = 3 people who get both questions wrong.

It's a bit of a twist, but it's still very interesting. 10 are all right, and 25 people are all right in the first question, which proves that only the first question is right = 25-10 = 15That is to say, these 15 people did the second question wrong, and 18 people in the class got the second question wrong, that is, there were three more people, and the second question was also wrong, and at the same time, these 3 people did not get the first question right.

In other words, none of these 3 people got any of the questions right. There are 28 people in the class. This question is very innovative, and one of the difficulties is that no one in the second question has done it right except for all the right people, which is not easy to think of.

I didn't make it at first, but I started from the topic itself and studied it carefully.

Problem solving ideas: understand the correct rate, the correct rate refers to the number of people who do the right questions in the total number of people who do the questions, the calculation method is: [the number of people who do the right questions The total number of people who do the questions] 100% = the correct rate, and you can answer it in this column

40 40+10] 100%=80%, Answer: The correct rate of this question is 80%;

So the answer is: 80, 6, 40 people do it right, 10 people do it wrong, so there are 40 10 50 (people) in total

So 40 50 ,2,80%,1,80%,1,80,1,math problem, 40 people in the class get it right and 10 people get it wrong, and the correct rate of this problem is (75)%,0,

The idea of a collection.

First of all, 25 people were correct in the first question, and 10 of them answered the second question correctly at the same time. That is, there are 15 people who only answered the first question correctly but did not answer the second question correctly.

After that, 18 people answered the second question incorrectly, and 15 people had already concluded that they had answered the first question correctly but answered the second question incorrectly.

Fifteen out of 18 people answered the first question correctly, so there are 3 people who get both questions wrong.