For the past n days, the average (arithmetic mean) daily production at a company was 50 units. If today's production of 115 units raises the average to 55 units per day, what is the value of n?
Choose the correct option:  A) 8  B) 10  C) 12  D) 14  E) 16
The daily production was raised by 5 units for n days, which has a weighting of 5n.   5n = 115-55= 
<gadget id="calculator">115-55</gadget>
<output>60</output>
60   n= 12   The answer is 12.
<result>C</result>
For the past n days, the average (arithmetic mean) daily production at a company was 50 units. If today's production of 115 units raises the average to 55 units per day, what is the value of n?