Answer:
The standard error is 0.033.
Explanation:
We are given that Sukie interviewed 125 employees at her company and discovered that 21 of them planned to take an extended vacation next year.
Let 
 = proportion of employees who planned to take an extended vacation next year
 = proportion of employees who planned to take an extended vacation next year 
 =
 = 
 =
 = 
 = 0.168
 = 0.168
n = number of employees at her company = 125
Now, the standard error is calculated by the following formula;
 Standard error, S.E. = 
 
 
 = 

 = 
 = 0.033
 = 0.033
Hence, the standard error is 0.033.