My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Thanks Tree1Thanks
  • 1 Post By greg1313
Reply
 
LinkBack Thread Tools Display Modes
November 25th, 2016, 08:41 AM   #1
JMC
Newbie
 
Joined: Nov 2016
From: USA

Posts: 5
Thanks: 0

need help with progression

Looking at the following progression which is dividing the first number (100) into two parts 100(.7) and 100(.3)(.9)
Then each number is also divided the same way (e.g. - 70(.7) and 70(.3)(.9)

I am then looking for a way to sum all of the numbers.

100
70 27
49 18.9 18.9 7.29
34.3 13.23 13.23 5.103 13.23 5.103 5.103 1.9683
JMC is offline  
 
November 25th, 2016, 08:56 AM   #2
Math Team
 
topsquark's Avatar
 
Joined: May 2013
From: The Astral plane

Posts: 2,256
Thanks: 926

Math Focus: Wibbly wobbly timey-wimey stuff.
Please do not double post.

-Dan
topsquark is online now  
November 25th, 2016, 08:58 AM   #3
JMC
Newbie
 
Joined: Nov 2016
From: USA

Posts: 5
Thanks: 0

I was really not sure what kind of math it is.
JMC is offline  
November 25th, 2016, 10:07 AM   #4
JMC
Newbie
 
Joined: Nov 2016
From: USA

Posts: 5
Thanks: 0

Does anyone have any ideas?
JMC is offline  
November 25th, 2016, 10:57 AM   #5
Global Moderator
 
greg1313's Avatar
 
Joined: Oct 2008
From: London, Ontario, Canada - The Forest City

Posts: 7,958
Thanks: 1146

Math Focus: Elementary mathematics and beyond
$100\cdot(0.97)^n$
Thanks from topsquark
greg1313 is offline  
November 25th, 2016, 02:10 PM   #6
JMC
Newbie
 
Joined: Nov 2016
From: USA

Posts: 5
Thanks: 0

How did you arrive at the .97?
JMC is offline  
November 25th, 2016, 02:24 PM   #7
JMC
Newbie
 
Joined: Nov 2016
From: USA

Posts: 5
Thanks: 0

Never mind,
Is it 1 - (.7 - .3(.9))
JMC is offline  
November 25th, 2016, 07:00 PM   #8
Global Moderator
 
Joined: Dec 2006

Posts: 20,919
Thanks: 2201

No. The sum of the numbers in the $n$th row (starting with $n$ = 1) is $100(0.97)^{{\large n} - 1}$.

The corresponding sum of the numbers in all $n$ rows is $10000(1 - 0.97^{\large n})/3$.

The 0.97 is the value of 0.7 + 0.3(0.9).
skipjack is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
progression



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Arithmetic Progression and Geometric Progression jiasyuen Algebra 1 May 1st, 2014 03:40 AM
Progression . jiasyuen Algebra 5 April 23rd, 2014 04:36 AM
progression panky Algebra 1 December 8th, 2011 09:32 AM
progression mikeportnoy Algebra 3 October 14th, 2008 01:42 AM
progression mikeportnoy Real Analysis 0 December 31st, 1969 04:00 PM





Copyright © 2019 My Math Forum. All rights reserved.