# Thread: Exponential decay

1. ## Exponential decay

I have the table
t Coffee
0 125
1 111
2 98
3 87
4 77
5 69
6 61
7 54
8 47
9 42
10 38
11 34
12 30
13 26
14 23
15 21
16 18
17 16
18 14
19 13
20 11
21 10
22 9
23 8
24 7

I have to work out the exponential decay using the formular y=ka^-mx +c but i am not even sure where to begin. Can anyone offer some help please.

2. Do you have Excel or some other program you can use?.

I ran your data through Excel and came up with an equation of

$\displaystyle y=124.96e^{-.1202t}$

3. I use excel and Autograph to do my graphs. How did u come up with that formular? And how do i plot this onto a graph? I am not even too sure where to start, so lost.

4. can any1 give me an example of what i need to do please.

5. Enter your data into Excel, then in the toolbar click on Insert, then Chart.

XY scatter, enter your data into the box and create your chart. Then,

click on Chart, Add Trendline, Click on the Options tab and make sure that

"Show equation on Chart" is checked. Also, check R^2. The closer it is to 1,

the better.

6. kool, got that. So what is this formular? how does it relate to my other formular in my original post?