Marks of the students in a particular subject of a class are given below.
 
Marks \(0 - 10\) \(10 - 20\) \(20 - 30\) \(30 - 40\) \(40 - 50\) \(50 - 60\) \(60 - 70\)
Number of students \(10\) \(13\) \(16\) \(14\) \(11\) \(9\) \(6\)
 
Find its standard deviation.
 
Answer:
 
The standard deviation is
 
(Note: Round off the answer to \(2\) decimal places.)