Jim's Market couldn't keep Crunchy Critter Crackers in stock. Jim started with 300 boxes but everyone wanted them. The first day Jim sold 6 boxes, and on the second day he sold 14 boxes. Each day 8 more boxes were sold than the day before. So after two days, he had sold 20 boxes. If he kept selling the crackers at this rate, when would Jim run out of Crunchy Critter Crackers?
A. 9 days
B. 12 days
C. 8 days
D. 14 days
6 + 8(n-1) is the arithmetic series starts at 6 boxes each day the number of boxes is increased by 8
sum of series (we are looking for 'n')
n/2 ( 6 + 8(n-1) ) = 300
n/2 ( 6 + 8n - 8) = 300
n ( -2 + 8n) = 600
-2n + 8n^2 - 600 = 0 quadratic formula shows n = 8.79 days on the 9th day he will run out of crackers !