Converges and Diverges

May 2010
5
0
Arithmetic word problem

The first row of seating in section H of the Concert Area has 7 seats. In all, there are 25 rows of seats in section H, each row containing 2 seats more than the row preceding it. How many seats are in section H?

My attempt:

it is an arithmetic problem i guess.
a1=7
a1+(n-1)d
7+(25-1)2=55 seats
is this how you do this problem?
 
Last edited:

Plato

MHF Helper
Aug 2006
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The first row of seating in section H of the Concert Area has 7 seats. In all, there are 25 rows of seats in section H, each row containing 2 seats more than the row preceding it. How many seats ?
\(\displaystyle \sum\limits_{k = 0}^{24} {\left( {7 + 2k} \right)} = ?\)
 
May 2010
5
0
Converge

im sorry i really do not understand what that means!
 

Plato

MHF Helper
Aug 2006
22,455
8,631
im sorry i really do not understand what that means!
I am sorry that I misunderstood.
I thought you were in a pre-calculus course.
Do you realize that you posted this in the pre-calculus forum?
 
May 2010
5
0
I am in pre calculus, however I do not understand the symbol of E we never learned that. I don't know what your trying to explain! Please help!
 

Plato

MHF Helper
Aug 2006
22,455
8,631
I am in pre calculus, however I do not understand the symbol of E we never learned that. I don't know what your trying to explain! Please help!
Are you really in a pre-calculus course in which the idea of summation is not considered?
It is very hard to believe that any pre-calculus course would not discuss the notation \(\displaystyle \sum\limits_{k = 0}^{24} {a_k } \).

I truly hope that your course will serve you future needs.
 
May 2010
5
0
I dont see how it makes any difference to you. This is a pre-calculus question and I need help. I see that I am not getting it from you!
 
Apr 2009
303
37
I dont see how it makes any difference to you. This is a pre-calculus question and I need help. I see that I am not getting it from you!
The first row has 7 seats, since k=0 zero when you are at the first row. If you move up to the second row k=1, so there are 7+2(1)=9 seats. If you move up to the third row k=2, so there are 7+2(2)=11 seats. You can continue this for k=3,...,24 (since there are 25 rows and we consider the first row to be row 0). The notation Plato posted tells you to add up each one of these terms. So,

\(\displaystyle \sum_{k=0}^{24}7+2k=7+9+11+13+...\), where \(\displaystyle k\) is the index of the summation, 0 is the lower bound (the initial value of k) and 24 is the upper bound (the final value of k). Thus, you begin at k=0 and add the following terms up until you get to k=24.

Hopefully that clears things up.
 
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