csateasy
The average marks of 100 students are given to be
- 40.It was found later that marks of one student were 53 which were misread as
- 83.The corrected mean marks are
- A.39
- B.39.7
- C.40
- D.40.3
▶ Answer & Explanation
Correct answer: B. 39.7
The total marks of 100 students were initially calculated based on a misread value of 83 instead of the correct value of 53. This means the total sum was overestimated by 83 - 53 = 30 marks. To find the corrected average, we subtract this excess from the total sum and then divide by the number of students. The corrected average is (Initial Total Marks - 30) / 100. Since the initial average was 40, the initial total marks were 40 * 100 = 4000. The corrected total marks are 4000 - 30 = 3970. Therefore, the corrected average is 3970 / 100 = 39.7.
Source: UPSC csat 2019