The mean increment for the monthly salary of the employees from company A is RM 456.5 with a standard deviation of RM 90.5. (i) Find at least what percentage of the employees receive an increment of RM 230.25 to RM 682.75. (ii) State the theorem used in part (i) and explain why the theorem is used.

(iii) If the mean and standard deviation of the increment of the employees from company B are RM 380.4 and RM 20.2 respectively. By comparing the relative variability (i.e. consistency) of company A and B, state the company that has higher variation of salaries increment.