[2025 CSAT] EBS: "Math is 'definitely' easier than last year's CSAT... No killer questions"

"Last year's question 22 was difficult to calculate due to fractions
This year, it is given as an integer, making calculation simple"

The mathematics section of the 2025 College Scholastic Ability Test (CSAT) was analyzed by the Korean Educational Broadcasting System (EBS) as being noticeably easier than last year's exam. It was explained that while the previous CSAT, which was the first to exclude so-called 'killer questions,' had a high perceived difficulty for question 22, this year's exam featured questions that were much easier to calculate.

At the '2025 CSAT Question Trend Analysis Briefing' held on the 14th at the Government Sejong Complex, Shim Ju-seok, a teacher from Incheon Haneul High School and a member of the EBS on-site teacher group analyzing the second session mathematics questions, said, "Some questions requiring comprehensive thinking might feel somewhat challenging to some test-takers, but overall, it is judged that the questions were clearly easier than last year's CSAT."

On the 14th, the day of the 2025 College Scholastic Ability Test, examinees are waiting for the exam to start at Gyeongbok High School in Jongno-gu, Seoul. Photo by Joint Press Corps

Teacher Shim emphasized, "A variety of difficulty levels were evenly presented. At the same time, questions that were not covered in the public school curriculum, questions requiring excessive calculations, or questions that could cause mistakes due to unnecessary concepts?so-called 'killer questions'?were excluded."

This year's exam matched the 'perceived difficulty' of the September mock test, which was easier than last year's CSAT. Teacher Shim stated, "Generally, if the September mock test and the CSAT are set at the same level, students naturally improve their scores by studying hard over two months. The primary goal of the CSAT is to make students feel a similar level of difficulty as in September. This year's CSAT was closer in difficulty to the September mock test than to last year's CSAT."

The highest standard score for the mathematics section in last year's CSAT was 148 points, while the September mock test this year had a highest score of 136 points.

EBS identified questions with discriminative power: question 22 in Mathematics I related to the inductive definition of sequences; question 21 in Mathematics II asking about the limit value of a function; question 29 in Probability and Statistics concerning the meaning and properties of the normal distribution; question 30 in Calculus involving inference of the shape of a function's graph; and question 30 in Geometry using the inner product of vectors.

The linkage rate with EBS textbooks was 50%, with 11 questions linked in the common subjects Mathematics I and Mathematics II, and 4 questions each linked in the elective subjects Probability and Statistics, Calculus, and Geometry. Teacher Shim explained, "The linkage in mathematics involves the application of conceptual principles and the use of transformed question materials. Notably, all the highly discriminative questions in Mathematics I were linked to EBS textbooks, and there were also questions with very similar problem-solving algorithms."

When asked if there were questions of similar difficulty to last year's question 22, which students found to be a 'killer question,' Teacher Shim replied, "There are no questions like last year's question 22." He added, "Last year's question 22 involved fractions in the process of finding coefficients. This required common denominators in equations, which might have made the process difficult. However, this year's question 15 featured function coefficients all given as integers from the start, making calculations simpler."

He also added that last year's question 22 was not a 'killer question.' Teacher Shim said, "(Question 22) differs from questions with excessive calculations, complex function inference processes, or those where using private education skills can shorten the time. Question 22 is by no means a killer."