For the past n days, the average (arithmetic mean) daily production at a company was 50 units. If today's production of 110 units raises the average to 55 units per day, what is the value of n? Choices: A) 9 B) 11 C) 13 D) 15 E) 17
The daily production was raised by 5 units for n days, which has a weighting of 5n.   5n = 110-55= 
<gadget id="calculator">110-55</gadget>
<output>55</output>
55   n= 11   The answer is 11.
<result>B</result>
For the past n days, the average (arithmetic mean) daily production at a company was 50 units. If today's production of 110 units raises the average to 55 units per day, what is the value of n?