This is a blog I've created to talk about what I have learned, resources I have found and tips/ideas I want to remember regarding elementary mathematics.
I hate to seem like I whining about math, because I'm really not, but I just find so many ideas and concepts that I don't get, I don't like or I don't remember (or that I don't find useful!). Recently, I have been asked to calculate compound interest. Before that, it was simple interest, and it stays true to it's name - it's pretty simple.
Compound interest, on the other hand, takes me a long time to work out. I never seem to get the right answer the first time. It's because there are so many different variables to work with and things to plug in. It makes my mind go crazy! But...if I take it slow and double check my work, I can usually get it to come out right, now that I've gone over the things I will share with you below.
So, here's the formula for compound interest:
A= P (1 + r/n) nt
where
P = future value
A= amount of initial deposit
r = interest rate (expressed as a fraction: eg. 0.06)
n = # of times per year interest is compounded
t = number of years invested
Here is the formula explained and an example of how to work a problem using that formula:
I don't think I've been this frustrated in a long time! I knew that things wouldn't stay easy for long in this class but I did not expect to get hung up like I was when I came upon calculating variance! I don't know how many times I worked these problems over in the homework and practiced them out of the book. I also followed examples and step-by-step instructions in the homework assignments, but I still could never come out with the right answer. Finally, I realized I had to take a deep breath, take a break, and come back to it.
When I finally came back to variance, I decided that the first thing I needed to do was SLOW DOWN. Then I needed to take each step one at a time and make sure that all the numbers I was plugging in were right and that I was completing each part of the steps. Once I slowed down and stopped panicking, I was able to think and calculate better (thank goodness!).
The definition of variance and how to find it is what threw me off. This can seem a little daunting:
(S^2) = summation[( x - mean)^2] / n-1
In easier terms, variance is computed as the average squared deviation of each number from its mean.
First, find the mean of the set of numbers you have.
Then, subtract the mean you calculated from each number in the set.
Now, square each number that you have come up with.
Finally, add those squared numbers together and divide them by the amount of numbers that existed in the original set.
For instance, for the numbers 1, 2, and 3, the mean is 2 and the variance found this way:
If this isn't helpful or you're still confused, you can watch this video. It was helpful for me! I can do this with or without a calculator, and the video show to use one, but you obviously don't have to. I think it's a good idea to do it without for the sake of becoming less dependent on them. This is doable! The following site was also great!
