SOLUTION: A theater is set up in such a way that there are 20 seats in the first row and 4 additional seats in each consecutive row. The last row has 212 seats. How many seats does the theat
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Question 1164130: A theater is set up in such a way that there are 20 seats in the first row and 4 additional seats in each consecutive row. The last row has 212 seats. How many seats does the theater have. Answer by solver91311(24713) (Show Source):
The first thing you need to know is the number of rows. The number of rows is the number of terms in this arithmetic sequence. We know the last term is 212 and we know the first term is 20. Furthermore, we know that the common difference is 4.
Subtract the first term from the last term, divide the result by the common difference, and then add 1 to get the number of terms (or rows of seats in this case).
The next thing is to find the sum of all the terms. Find the average of the first and last terms, that is add the first term to the last term and divide the result by 2. Then multiply that result by the number of terms (rows) that you discovered in the first step.
John
My calculator said it, I believe it, that settles it
