The CBSE's decision to order retests in the Class X Mathematics and Class XII Economics papers after complaints that they had been leaked has sparked a flurry of queries about the board and its examinations.

Here are the answers to some frequently asked questions on the annual school exams conducted by the all-India Central Board of Secondary Education: 

Q: How many students appeared for the CBSE board exams in 2018? 

A: CBSE is the largest education board in the country conducting every year 24 types of exams, including, for the time being, the NEET test for admission to medical colleges. The board conducts the Class 10 and Class 12 exams of schools affiliated to the CBSE.

This year, 16,38,428 students are appearing for the Class 10 CBSE board exams and 11,86,306 students for Class 12.

Q: What percentage of students across India come under the board? 

A: About nine per cent of the total number of students across all boards who appear in such examinations are under the CBSE. The total number of students sitting for class 10 exams of all boards put together is roughly 1.86 crore and 1.45 crore for class 12.

Q: What is the duration of the CBSE exams? 

A: Examinations for Class 10 and Class 12 started on March 5. The Class 10 exams were scheduled to conclude on April 4 and the Class 12 exams on April 13.

Q: When does the process of preparing the questions start? 

A: The preparations begin at least six months before the start of the board exams and as soon as the registration for the exams ends at the school level.

Q: How are the question papers set? 

A: The questions are framed, examined and finalised in two stages. In the first stage, CBSE sets up a four or five member committee, comprising school and college teachers, for each subject. The committee prepares a question bank, arranges them into three sets of question papers -- for Delhi schools, the rest of the country and overseas schools.

In the second stage, the questions are checked by an expert committee constituted by the CBSE to see if laid-down standards have been followed with regard to the syllabus, difficulty level and length of the paper. The question sets are then finalised by the committee maintaining upmost secrecy.

Q: How are the question paper sets different from each other? 

A: As against the earlier practice when 70 per cent of the questions would vary from one set to another, the questions now prepared remain largely the same, except for the sequencing. A leak in any one set compromises the other question sets.

Q: What procedures are followed in the run-up to the exams? 

A: In accordance with standard procedures, the question papers are received at the examination centres in sealed packages and opened in the presence of at least four assistant superintendents -- one of them being from the school other than the examination centre as a witness.

Full-time observers are also posted at sensitive centres in Delhi and outside. The board also remains in touch with the state machinery and the local police to ensure trouble- free examinations throughout the country.