Answer: Because 65+55+45+35=200 and 65,438+000 people were doing the questions, everyone answered two questions correctly.
That is, 200/2= 100 (person) is the number of people who write the questions. So we thought (65+55)-(45+35) = 40,40/2 = 20 (person). Are there 20 more students who answered questions 1 and 2 correctly than those who answered questions 3 and 4 correctly? The answer is yes. Because of the two parts of the question, the other answers are just equal, and the difference is just eliminated.
So we can imagine that there are more people who answer one or three correctly at the same time than two or four at the same time.
[(65+45)-(55+35)]/2= 10 (person); There are as many people who answer one or four correctly as there are people who answer two or three correctly at the same time.
(65+35)-(55+45)=0.
Is that really the case? We might as well analyze it.
If the condition is 170 right answers, 260 right answers, 340 right answers and 430 right answers, then we can easily make four questions, 35, 30, 20, 15 respondents, and each person answers two questions.
But every condition is odd, so it seems that the serial numbers of the questions must be crossed. How to match it properly? The conditions that must be met here are: the total number of respondents is 100, and each person answers 2 questions correctly, which is consistent with the problem set. So there are two matching methods:
① ② A group, ③ 4A group; ① ③ is group A and ② is group B. In order to "compress" 200 into 100, we make full use of resources and include one of them in another graph.
Thus, there is: A The answers to the four questions are as follows: 20 people answered correctly 12, 45 people answered correctly 13, 35 people answered correctly 24, and no one answered correctly 34, that is, 20 people answered correctly 12 to 34, 65,438+00 people answered correctly/kloc-0.
B The answers to the four questions are: 10/4 right answers, 55 right answers 12, 35 right answers and 34 right answers.
Among them, there were 20 people who answered ① ② more than ③ and ③ correctly, and there were 10 people who answered ② and ③ correctly at the same time, and both were zero.
That is, the previous judgment was correct.
The above is for reference.