
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
 LinkBack  Thread Tools  Display Modes 
April 8th, 2015, 12:11 PM  #1 
Newbie Joined: Apr 2015 From: London Posts: 1 Thanks: 0  Set Percentage then a set figure
Hi, I am completely useless as maths, so I know this forum is my haven! Basically, I use a software which allows me to automatically increase a price from one source to another source based on a % increase from the original price. My problem is probably very easy to answer; basically, I have 2 percentages to add and then a set £0.20, so for example: 7% + 3.4% = 10.4% + 20p, but I need this to be in one % of the original figure, is this possible? Many thanks in advance. Last edited by skipjack; April 9th, 2015 at 03:20 AM. 
April 8th, 2015, 01:16 PM  #2  
Global Moderator Joined: May 2007 Posts: 6,756 Thanks: 696  Quote:
Last edited by skipjack; April 9th, 2015 at 03:21 AM.  
April 9th, 2015, 01:46 AM  #3 
Senior Member Joined: Apr 2014 From: Glasgow Posts: 2,155 Thanks: 731 Math Focus: Physics, mathematical modelling, numerical and computational solutions 
How's your algebra? An algebraic function describing what you stated is: $\displaystyle P_{new} = \left(1+ \frac{p_i}{100\%}\right)P_{old} + P_{add}$ where $\displaystyle P_{new}$ = new price of item $\displaystyle P_{old}$ = old/original price of item $\displaystyle p_i$ = percentage increase (e.g. 15%) $\displaystyle P_{add}$ = price to add Then the net percentage increase after the operation above is given by $\displaystyle p_{net} = \left(\frac{P_{new}}{P_{old}}  1\right) \times 100 \%$ For example, using the numbers you gave... $\displaystyle p_i = 10.4\%$ $\displaystyle P_{add} = 20$p and some old price... let's say $\displaystyle P_{old} = 80$p $\displaystyle P_{new} = \left(1+ \frac{10.4\%}{100\%}\right)\times 80 + 20$ $\displaystyle = (1.104 \times 80) + 20$ $\displaystyle = 108.32$p We can now calculate the net percentage increase: $\displaystyle p_{net} = \left(\frac{108.32}{80}  1\right) \times 100\%$ $\displaystyle =(1.354  1) \times 100 \%$ $\displaystyle = 35.4\%$ Last edited by Benit13; April 9th, 2015 at 01:56 AM. 

Tags 
figure, percentage, set 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
I cant figure this out! please help  rdaloian  Algebra  5  January 17th, 2015 07:18 PM 
the figure  mared  Geometry  1  July 6th, 2014 03:16 AM 
help!! cant figure it out...!  himybrother  Real Analysis  2  October 19th, 2009 04:24 PM 
How To Figure Gross With a Certain Net Figure  Al_Ch  Elementary Math  2  May 21st, 2009 05:53 PM 
I cannot figure this out at all?  flyaway  Algebra  6  March 10th, 2009 08:42 PM 