Expert: Scotto - 11/11/2008

Question
QUESTION: in a exponential growth and decay modeling data formula how do you calculate f(t)=30,000/1+20e-1.5(4). How do I calculate this using my scientific calculator and get the right answer.

ANSWER: Note that 1.5*4 is 6 - no need to calculate that.

Type the following
30000 <enter>
1 <enter>
20 <enter>
1 <exp> <times> +
6 <subtract> <divide>

I'm not sure you can view it, but the stack will hold, after each step
Entering 30000 will give you 30000 in the stack.
Entering 1 will give you 1, 30000 in the stack.
Entering 20 will give you 20, 1, 30000 in the stack.
Entering 1 will give you 1, 20, 1, 30000 in the stack.
Entering <exp> will give you 2.718281828..., 20, 1, 30000 in the stack.
Hitting the <times> key will give you 54.36563657, 1, 30000 in the stack.
Hitting the <plus> key will give you 55.36563657, 30000 in the stack.
Hitting the <divide> key will give you the answer a little less than
550. (Now I wouldn't want to say it exactly, or you wouldn't have to do anything).





---------- FOLLOW-UP ----------

QUESTION: I need help with polar coordinate. This is what I have. There are four circles of horses. Each circle is three feet from the next circle. The radius of the inner circle is 6 Feet.IF a horse in the inner circle is 5/6 of the way around the merry-go-round, give its polar coordinates.

Answer
If the inner hourse is in question, the radius is 6 feet.

That would mean the distance he has to travel is 36π, but that's not important.

If he is 5/6 of the way around, that is equivalant 5π/3 radians.

The formula to use convert polar to rectangular.

They are y = rsin(π) amd x = rcos(π)