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Homework Help: Increasing Row Size

  1. Nov 17, 2007 #1
    Increasing Row Size....

    1. The problem statement, all variables and given/known data
    There are 150 rows at a concert hall. Each row you move back there is an increase of 10% in the number of seats. The first row has 100 seats. How many seats are there in the concert hall?

    2. Relevant equations
    I don't know the equation to represent this change.

    3. The attempt at a solution
    Obviously I could go through and do each rows amount of seats, but I'd like to know the equation that will solve this. Is it n(n+1)/2?
  2. jcsd
  3. Nov 17, 2007 #2


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    Homework Helper

    It's called a geometric series. The number of seats in the nth row is 100*(1.1)^n (where n=0 is the first row). Now find a reference and look for 'geometric series'.
  4. Nov 17, 2007 #3


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    Homework Helper

    Notice that the number of seats in each successive row increases by a constant proportion, that is, each row has 1.10 times as many seats as the preceding row. What kind of a sequence is this?

    If you have to add a finite number of terms of a sequence of this type, what formula do you use?
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