A large publishing company awards a 14% salary increase to every employee. Which of the following statements about the distribution of the company’s salaries is/are correct? 1 The standard deviation will remain unaltered 2 The standard deviation will increase by 14% 3 The coefficient of variation will remain unaltered ? 1 and 2 only ? 1 and 3 only ? 2 and 3 only ? 1, 2 and 3
If everybody’s salary increases by 14% then the mean will also increase by 14%.
All of the variations from the mean will also increase by 14%, and so the standard deviation will increase by 14% (so statement 2 is correct).
The coefficient of variation is the standard deviation divided by the mean. So if they both increase by 14% it will remain the same (so statement 3 is correct also).