The mean of marks obtained by 32 student is 42 if one mark of 20 was instead as 28 find the correct mean mark

Number of students = 32
Incorrect mean = 42
Total sum of marks (incorrect) = Number of students × Incorrect mean
Total sum of marks (incorrect) = 32 × 42
Total sum of marks (incorrect) = 1344

Incorrect mark entered = 28
Correct mark should have been = 20
Difference = Incorrect mark - Correct mark = 28 - 20 = 8
Since the entered mark was higher than the actual mark, we need to subtract this difference from the total sum.

Correct total sum of marks = Total sum of marks (incorrect) - Difference
Correct total sum of marks = 1344 - 8
Correct total sum of marks = 1336

Correct mean mark = Correct total sum of marks / Number of students
Correct mean mark = 1336 / 32
Correct mean mark = 41.75

The correct mean mark is 41.75.