In Company J, the total monthly payroll for the 15 factory workers is $30,000 and the total monthly payroll for the 30 office workers is $75,000. By how much does the average (arithmetic mean) monthly salary of an office worker exceed that of a factory worker in this company?
Choose the correct choice from the following options.
A) $450 B) $500 C) $600 D) $650 E) $750
The average monthly salary of a factory worker is: $30,000 / 15 = $2000.   The average monthly salary of an office worker is: $75,000 / 30 = $2500.   The difference in average salary is: $2500 - $2000 = $500.   The answer is $500.  2500 -  2000= 
<gadget id="calculator">  2500 -  2000</gadget>
<output>500</output>
$500.   The answer is $500.
<result>B</result>
In Company J, the total monthly payroll for the 15 factory workers is $30,000 and the total monthly payroll for the 30 office workers is $75,000. By how much does the average (arithmetic mean) monthly salary of an office worker exceed that of a factory worker in this company?