# A simple investment question.

Discussion in 'Community' started by coopdog, Feb 24, 2005.

1. ### coopdog macrumors 6502a

Joined:
Oct 5, 2002
Location:
The Great Midwest
#1
Hey guys an investment question,
If I earn 85% in year one but then lose 50% in year 2 what was my avarage percentage gain over the last two years?

Also does compounding effect the calculation?

Thanks guys!

2. ### Sun Baked macrumors G5

Joined:
May 19, 2002
#2
7.5% net loss over two years.

But compounding always affects the calculation...

Joined:
Oct 11, 2004
Location:
Saint Charles, MO
#3
Compounding would effect it, and I think you still be looking at a 15% gain or something, not sure though, that is a guess.

4. ### MacAztec macrumors 68040

Joined:
Oct 28, 2001
Location:
San Luis Obispo, CA
#4
I think you lose a bit of money. Say you start with 1000 dollars.

85% gain, you are at \$1,850 dollars. Then, year 2 comes, and you lose 50%...

That puts you at \$925.

### Staff Member

Joined:
Sep 19, 2002
Location:
Los Angeles
#5
I'll add my 2 cents worth.

MacAztec is right. You end up with \$925.

Now you want to know the average percentage gain. I don't know the definition of this term, but my guess is that it means the percentage which, if it was applied each year with compounding, would produce the same result as your actual experience.

So you want to know what equivalent two-year rate of interest, call it p, would produce \$925 from \$1000 in two years, i.e., 1000 x p x p = 925, which you'd solve for p and get 0.96177, meaning you end up each year with about 96.177% of what you stared with, i.e., about a 3.823% loss.

Instead of starting from an assumed value (\$1000) and the results of working out the final amount you have (\$925), you could also compute the average percentage gain directly from the percentages given in the problem: squareroot(1.85 * 0.50) - 1 = 0.96177 - 1 = -0.03823.

So the average percentage gain is -3.823%, which you'd more likely call an average percentage loss of 3.823%.

We can check it. If we did things right, your two-year investment experience should produce the same result as a 3.823% loss each year, compounded.