Math Help

Archive for February, 2007

Question: I need some help with a math problem?

This is from a chapter for exponential and logarithmic functions.
The formula: [A=P(1+ r/n)^nt]
***Amount invested= $5000 (P)
***# of compounding periods = 360 (n)
***Annual Interest rate= ?? (r)
***Accumulated Amount = $9000 (A)
***Time in Years= 4 (t)

I am supposed to solve for (r)… I have no clue! Thanks for help on this!

Answer: A = P (1 + r/n)^nt

Substitute in what you know.

9000 = 5000 (1 + r/360) ^ (360*4)
Divide both sides by 5000.
9/5 = (1 + r/360) ^ (1440)
“Raise” both sides to log.
log (9/5) = log (1 + r/360) ^ (1440)
Use the property that lets you move the exponents to the left of log.
log (9/5) = 1440 log (1 + r/360)
Divide both sides by 1440.
(log (9/5)) / 1440 = log (1 + r/360)
Use a calculator to figure out the left part.
1.77272573E-4 = log (1 + r/360)
Rewrite in exponential form.
10^1.77272573E-4 = 1 + r/360
1.000408269 = 1 + r/360
Subtract 1 from both sides.
0.000408269 = r/360
Multiply both sides by 360.
0.146977 = r
Turn that into a percentage.
r = 14.698% or about 14.7%

hope i helped

Properties of Logarithms – Part 1

Question: Is there an easier way to understand positive & negative numbers in math, other than what these teachers in t?

I have a learning disability in math (discalculia) and math teachers don’t seem to understand, is there anyone out there that can help, especially right now positive and negative numbers

Answer: Plus and minus mean opposite directions.

If i owe money i could say i have minus money. It’s just a way of saying the same thing (that suits science and computers).

I can say many weird things. Like i don’t hate avoiding hunger. I like eating. 2 pairs of negatives which cancel each other out, producing a positive.

negative and positive are just opposites. we choose which way round they are.

In maths,

Down 10 means up minus ten.

ie take away 10 means add (-10)

If you learn a computer language you’ll find this very useful.

To add a negative amount is to subtract.

To subtract a negative amount is to add.

Positive times negative = a negative number of positive lots, or a +ve number of -ve lots, subtraction either way.

Negative times negative = a negative number of negative lots, a subtraction of a negative number, or addition.

Adding/Subtracting negative numbers