Register    Login    Search    Rss Feeds

Forums Home » Ask An Instructor » GMAT Math » Manhattan GMAT Math Strategy Guides


 Page 1 of 1 [ 5 posts ] 



  Print view Print view Previous topic Previous topic | Next topic Next topic
 

Word Tranlations Chap 6 No. 6 Fourth Edition

Author Message
afvatcha
 Post subject: Word Tranlations Chap 6 No. 6 Fourth Edition
 Post Posted: Mon Jul 25, 2011 7:05 am 
Offline
Course Students


Posts: 34
Hi,

I looked at no. 6 of chapter 6 in the word tranlations book. The answer is 244.5. The answer key says 6 + (159 x 3)=483. 483/2=244.5.

My question is why is it 159 x 3. If there are 160 terms, shouldnt it be (160 x 3) + 6?

Thanks,
Anosh
Top 
mithunsam
 Post subject: Re: Word Tranlations Chap 6 No. 6 Fourth Edition
 Post Posted: Sat Aug 06, 2011 9:24 am 
Offline
Course Students


Posts: 76
Last term is calculated as first term + (n-1)d, where d is the difference and n is the number of terms.

So, it is 6 + (160-1)3 = 6+159*3 = 483

Alternatively, you can also write last term as 161 * 3 = 483

1st term is 6 = 3.2
2nd term is 9 = 3.3
3rd term is 12 = 3.4
---
---
160th term will be 483 = 3.161

Does that make sense?
Top 
afvatcha
 Post subject: Re: Word Tranlations Chap 6 No. 6 Fourth Edition
 Post Posted: Fri Aug 12, 2011 7:25 am 
Offline
Course Students


Posts: 34
mithunsam wrote:
Last term is calculated as first term + (n-1)d, where d is the difference and n is the number of terms.

So, it is 6 + (160-1)3 = 6+159*3 = 483

Alternatively, you can also write last term as 161 * 3 = 483

1st term is 6 = 3.2
2nd term is 9 = 3.3
3rd term is 12 = 3.4
---
---
160th term will be 483 = 3.161

Does that make sense?


Hi, Thanks! Where did you get this formula? Is it possible for an instructor who can verify this?
Top 
mithunsam
 Post subject: Re: Word Tranlations Chap 6 No. 6 Fourth Edition
 Post Posted: Fri Aug 12, 2011 10:12 am 
Offline
Course Students


Posts: 76
The formula is mentioned in OG.

You can think in this way...
You have the first term, say 1 and the difference between terms is 3
Now what is 9th term?
9th term is 8 terms away from the first term.

Therefore, it is 1 + 8*3 = 25. In another words 1 + (9-1)3 = 25. (Where n = 9 and d = 3 in this particular example )

afvatcha wrote:
mithunsam wrote:
Last term is calculated as first term + (n-1)d, where d is the difference and n is the number of terms.

So, it is 6 + (160-1)3 = 6+159*3 = 483

Alternatively, you can also write last term as 161 * 3 = 483

1st term is 6 = 3.2
2nd term is 9 = 3.3
3rd term is 12 = 3.4
---
---
160th term will be 483 = 3.161

Does that make sense?


Hi, Thanks! Where did you get this formula? Is it possible for an instructor who can verify this?
Top 
jnelson0612
 Post subject: Re: Word Tranlations Chap 6 No. 6 Fourth Edition
 Post Posted: Sat Sep 17, 2011 9:47 pm 
Offline
ManhattanGMAT Staff


Posts: 1857
Thanks all, and yes, consider this formula verified.

_________________
Jamie Nelson
ManhattanGMAT Instructor
Top 
Display posts from previous:  Sort by  
 
 Page 1 of 1 [ 5 posts ] 





Who is online

Users browsing this forum: No registered users and 1 guest

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: