The arithmetic mean and standard deviation of a series of 20 items were calculated by a student as 20 cms and 5 cms respectively. But, while calculating them, an item 13 was misread as 30. Find the...

Extracted text: The arithmetic mean and standard deviation of a series of 20 items were calculated by a student as 20 cms and 5 cms respectively. But, while calculating them, an item 13 was misread as 30. Find the correct arithmetic mean and standard deviation.