Question

The mean marks of 100 students were found to be 40. Later on, it was discovered that a score of 53 was misread as 83. Then, the correct mean is .

• A. 37.5
• B. 35.6
• C. 39.7
• D. 38.7

Answer 1

The correct option is C 39.7

Mean = 40 and number of students = 100 [Given]
Total number of marks = 40 x 100
= 4,000
The correct sum of observations = 4,000+53-83
= 4000-30 = 3970

Therefore, Correct mean = $\frac{3970}{100}$
= 39.7