An outdoor amphitheater has 100 seats in the front row and each subsequent row has 6 more seats than the previous row. how many seats are in in the amphitheater if there are 23 rows?

If each row have 6 more seats than the previous, then there is a common difference of 6 seats. This, in turn, becomes an arithmetic progression, with a₁ being 100 and d being 6. Now, we want to know the total number of seats when n = 23, so we need to use the sum of an arithmetic progression form:






Hence, there are 3818 seats in the first 23 rows.

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