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#1 2016-06-15 03:30:00
- markosheehan
- Member
- Registered: 2016-06-15
- Posts: 51
sequences
a lecture theatre has a trapezium shaped floor plan so that the number of chairs in successive rows are in arithmetic sequence.the back rows of chairs contain 8 chairs and the front row contains 30. there are 12 rows altogether. 1.find the number of seats in the theatre 2. find the percentage of seats that are in the rear half of the theatre i cant work this out?
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#2 2016-06-15 03:56:21
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: sequences
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#3 2016-06-15 04:33:49
- thickhead
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- Registered: 2016-04-16
- Posts: 1,086
Re: sequences
{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}
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#4 2016-06-15 04:44:15
- ElainaVW
- Member
- Registered: 2013-04-29
- Posts: 580
Re: sequences
Hello:
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#5 2016-06-15 04:49:59
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: sequences
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#6 2016-06-15 05:11:21
- markosheehan
- Member
- Registered: 2016-06-15
- Posts: 51
Re: sequences
they are the right answers but how did you work it out?
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#7 2016-06-15 05:15:35
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: sequences
School problems have nice neat solutions. There is a reason for that. You can stumble through those arithmetic sequence formulas or you can play with the arithmetic for a couple of minutes.
Let us play with the arithmetic for a while.
Last row = 8
First row =30
Arithmetic sequences have the same difference from one number to the next. Everyone is familiar with the concept of counting by a number.
Try a difference of 2.Same as counting by 2.
8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30
12 rows from 8 to 30. Does that work for you?
No algebra required.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#8 2016-06-15 05:46:13
- ElainaVW
- Member
- Registered: 2013-04-29
- Posts: 580
Re: sequences
Hello:
Formula for an arithmetic sequence nth term.
{30,28,26,24,22,20,18,16,14,12,10,8} are how the seats are put.
Last edited by ElainaVW (2016-06-15 06:11:00)
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#9 2016-06-15 06:04:04
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: sequences
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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