Explanation
Correct answer: D.
Choice D is correct. The mean amount of time that the employees worked for the company is years. This means that the total number of years all employees worked for the company is years. After the employee left, the mean amount of time that the remaining employees worked for the company is years. Therefore, the total number of years all employees worked for the company is years. It follows that the number of years that the employee who left had worked for the company is years.
Desmos solution:
Note: Subtract the remaining employees' total years from the original total years.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect; this is the change in the mean, which isn't the same as the amount of time worked by the employee who left.
Choice B
Choice B is incorrect and likely results from making the assumption that there were still employees, rather than , at the company after the employee left and then subtracting the original mean of from that result.
Choice C
Choice C is incorrect and likely results from making the assumption that there were still employees, rather than , at the company after the employee left.