
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
 LinkBack  Thread Tools  Display Modes 
July 18th, 2019, 04:53 AM  #1 
Senior Member Joined: Aug 2014 From: India Posts: 458 Thanks: 1  Why principal is taken as 10 instead of 100?
If the S.I for 6 years be equal to 30% of the principal, it will be equal to the principal after how many years? Sol: $\displaystyle → 3 = 10*6*\large\frac{R}{100}$ $\displaystyle → R = 5%$ $\displaystyle → 10 = 10*T*\large\frac{5}{100}$ $\displaystyle → T = 20 yrs$ Why principal is taken as 10 instead of 100? Last edited by Ganesh Ujwal; July 18th, 2019 at 04:56 AM. 
July 18th, 2019, 06:23 AM  #2 
Senior Member Joined: Jun 2019 From: USA Posts: 120 Thanks: 40 
It doesn't really matter, since that is not necessarily the principal. The important thing is the 3 is 30 % of the 10. You could write it as 30 = 100*6*(R/100). More importantly, since simple interest is proportional to time, $\displaystyle \frac{I_1}{T_1} = \frac{I_2}{T_2} \rightarrow T_2 = (\frac{100 \%}{30 \%})(6~years) = 20~years$ 
July 18th, 2019, 07:08 AM  #3 
Senior Member Joined: Apr 2014 From: UK Posts: 953 Thanks: 340 
I took the wordy approach: If we get 30% after 6 years, that's 30%/6years = 5% per year. 100%/5% per year is 20 years 

Tags 
100, pricipal, principal 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Principal value  Kinroh  Calculus  2  April 16th, 2016 05:42 PM 
Principal Value  WWRtelescoping  Complex Analysis  1  April 23rd, 2014 11:57 PM 
Principal Value  aaronmath  Complex Analysis  1  September 24th, 2013 10:26 AM 
Principal value  Singularity  Complex Analysis  1  October 14th, 2010 08:37 AM 
Principal value of i^i  HairOnABiscuit  Complex Analysis  1  November 27th, 2009 04:40 PM 