If all the employees of a company fall into one and only one of 3 groups, \(X, Y,\) or \(Z,\) with 250, 100, and 20 members in each group, respectively, what is the average (arithmetic mean) weekly salary of all the employees of this company, if all employees are paid every week of the year?

(1) The average (arithmetic mean) annual salary of the employees in Group \(X\) is $10,000, in Group \(Y\) $15,000 and in Group \(Z\) $20,000.
(2) The total annual payroll is $4,400,000.

[spoiler]OA=D[/spoiler]

Source: GMAT Prep