SOLUTION: the corner section of a football stadium has 15 seats in the first row and 40 rows in all. Each successive row contains two additional seats. How many seats are in this section?
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Question 1104779: the corner section of a football stadium has 15 seats in the first row and 40 rows in all. Each successive row contains two additional seats. How many seats are in this section?
This is calculus. Answer by greenestamps(13200) (Show Source):
First row has 15 seats; each successive row has 2 more seats than the previous row; there are 40 rows in all.
Since the same number of additional seats is added in each successive row, the number of seats in the 40th row is 15+39(2) = 15+78 = 93.
There are 40 rows of seats; again since there are 2 additional seats in each successive row the average number of seats in each row is the average of the numbers of seats in the first and last rows. Then the total number of seats is that average, multiplied by the number of rows:
