For the past n days, the average (arithmetic mean) daily production at a company was 60 units. If today's production of 90 units raises the average to 62 units per day, what is the value of n ? Choose the correct choice from the following answers
A) 30
B) 14
C) 10
D) 9
E) 7
(average production for n days) * n = (total production for n days) --&gt; 60n=(total production for n days);   (total production for n days) + 90 = (average production for n+1 days) * (n+1) --&gt;60n + 90 = 62 * (n+1) --&gt; n=14.   Or as 30 extra units increased the average for n+1 days by 2 units per day then 30/(n+1)=2 --&gt; n=14.   Answer: 14.
<result>B</result>
For the past n days, the average (arithmetic mean) daily production at a company was 60 units. If today's production of 90 units raises the average to 62 units per day, what is the value of n ?