
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
 LinkBack  Thread Tools  Display Modes 
January 10th, 2017, 08:05 AM  #1 
Newbie Joined: Jan 2017 From: London Posts: 4 Thanks: 0  Looking for a formula to work out new values based on changing the Max and Min of...
Hi, not sure if this is the best place to ask  please let me know if there's a more suitable forum. I've got an irregular range of values ranging from infinity to 1 (randomizes every time). I want to be able to set a new value for the max and min values, and adjust everything in the range so that they stay in position relative to each other. For example, let's say I have ten values. The lowest is 40 and the highest is 8. I decided I want to make the highest one 0 and the lowest 10. I need to increase the lowest by 30, but the highest by only 8. I then need to increase the numbers in between each by a unique value so that they are in the same position relatively (but over a much smaller range). Anyone able to offer any assistance? Thanks. Last edited by skipjack; January 10th, 2017 at 01:03 PM. 
January 10th, 2017, 12:55 PM  #2 
Senior Member Joined: Feb 2010 Posts: 624 Thanks: 98 
A simple linear transformation comes to mind. Make two points from the information and find the equation of the line. In your example, you want $\displaystyle 40$ to map to $\displaystyle 10$ and you want $\displaystyle 8$ to map to $\displaystyle 0$. So make two points $\displaystyle (40,10)$ and $\displaystyle (8,0)$. From these two, make an equation for a line. The slope is $\displaystyle \frac{010}{840} = \frac{10}{32} = 0.3125$. So an equation for the line is $\displaystyle y = 0.3125x + 2.5$ 
January 10th, 2017, 01:05 PM  #3 
Global Moderator Joined: Dec 2006 Posts: 17,728 Thanks: 1360 
Do the values have to be integers?

January 11th, 2017, 12:46 AM  #4 
Newbie Joined: Jan 2017 From: London Posts: 4 Thanks: 0 
mrtwhs  thanks for the formula! I shall put this into system today and see if it fits what I'm trying to do. skipjack  no it doesn't. in fact I doubt it would work with just integers. Thanks guys 
January 20th, 2017, 02:03 AM  #5 
Newbie Joined: Jan 2017 From: London Posts: 4 Thanks: 0 
Hi folks, sorry I haven't had a chance to look into this for a while. mrtwhs  your formula works perfectly for the above criteria, but I was wondering if we could take it a step further. Basically, all the values are variable, so the original highest and lowest, and the new values, can all change. So I need to incorporate this into the formula. I've been trying a few things but can't get my head around it. Any chance you can think of a solution? Many thanks! 
January 23rd, 2017, 12:06 AM  #6 
Senior Member Joined: Apr 2014 From: UK Posts: 768 Thanks: 290 
I think what you want is this: Transform a number? 
January 24th, 2017, 05:50 AM  #7 
Newbie Joined: Jan 2017 From: London Posts: 4 Thanks: 0 
That's EXACTLY what I'm looking for! thanks weirddave!

January 24th, 2017, 06:23 AM  #8 
Senior Member Joined: Apr 2014 From: UK Posts: 768 Thanks: 290 
No problem, the most challenging part was trying to find it, I did it longer ago than I thought....


Tags 
based, changing, formula, forumula, max, min, values, work 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Changing the subject of a formula  adamfoley  Algebra  2  March 23rd, 2013 02:05 PM 
Changing Numbers To Prescribed Values Under Special Limitati  perry  Algebra  5  February 11th, 2013 06:35 AM 
formula for calculating an changing percentage  Leander  Applied Math  0  February 3rd, 2012 01:04 PM 
Changing the subject of a formula  poochie03  Algebra  1  September 10th, 2011 01:10 PM 
Changing the subject of a formula  chuckienz  Linear Algebra  1  May 6th, 2009 06:23 PM 