How Do You Calculate Investment Percentage Changes Correctly?

  • Context: High School 
  • Thread starter Thread starter grandnat_6
  • Start date Start date
  • Tags Tags
    Loss
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
3 replies · 4K views
grandnat_6
Messages
69
Reaction score
0
Hi,

I think I confused myself. Must be working too hard or something.

I trying to find the percentage gain or loss of an investment.

example:

1. orginal investment $10000.00 today $9,500.00

9,500.00/10,000.00 = .95*100 = 95%

Therefore I have 95% of my orginal amount or (100%-95%)= 5% loss.

10,000.00*-5%= -500

10,000.00-500= 9,500.00

Or:

10,000.00-9,500.00= 500.00

500.00/9,500.00= .05263*100=5.263%

9500*5.263=500

500+9,500.00= 10,000.00

Please straighten me out on this! They both seem to get me the correct answer but the percentages are different, which one is correct?

What if I started out with $9,500.00 and today it's $10,000.00?

Thanks.
 
Physics news on Phys.org
grandnat_6 said:
Hi,

I think I confused myself. Must be working too hard or something.

I trying to find the percentage gain or loss of an investment.

example:

1. orginal investment $10000.00 today $9,500.00

9,500.00/10,000.00 = .95*100 = 95%

Therefore I have 95% of my orginal amount or (100%-95%)= 5% loss.

10,000.00*-5%= -500

10,000.00-500= 9,500.00

Or:

10,000.00-9,500.00= 500.00

500.00/9,500.00= .05263*100=5.263%

9500*5.263=500

500+9,500.00= 10,000.00

Please straighten me out on this! They both seem to get me the correct answer but the percentages are different, which one is correct?

What if I started out with $9,500.00 and today it's $10,000.00?

Thanks.


UIt is not the same way up as way down in percentages:

if you began with $10,000.00 and after some time you have $9, 500.00 then you've lost 5% of your original invesment, as
$$\frac{9,500}{10,000}=0.05\Longrightarrow 0.05\cdot 100 \%=5\%\,\,\text{loss}$$
as the final amount is less than the first one.

Had you begun with $9,500.00 and after some time you had $10,000,, then you'd have won
$$\frac{10,000}{9,500}=1.05263\Longrightarrow (1-1.05263)\cdot 100\%=5.6263\%\,\,\text{profit}$$

DonAntonio
 
The "percentage change" is always relative to the initial amount. Going from 10000 to 9500 is a decrease of 500 so a percentage change of -500/10000= -.05 or -5% of 10000.

But an increase from 9500 up to 10000 is an increase of 500 and so a percentage change of 500/9500= .0526 or 5.26%.
 
Thanks for the help! I understand now.