Use excel to create empirical cumulative distribution function (CDF) and then use the CDF to find probabilities

[exlover]

Hi Everyone,

I hope you can help me in this problem. I have a set of observed data and created an empirical cumulative distribution using excel. I want to use this CDF to find probabilities like P(x<X) or P(X1 < x < X2 ).

The way I created the CDF is arrange the data in ascending order and then create a column next to it with the probabilities. I dont know how to attach the file but here is a sample below.
I have 4121 records and the sample here is for 4 records. Once I have this calculation done, the curve is plotted using xy scatter plot for Data in the x-axis and Probability in the Y-axis. This is how I created the CDF.

My question now is in case I wanted to find the probability is below 2.5. P(x<=2.5) how can I find it ? or if i want to find P( 970 < x < 980 ) ?

I hope there is an easy way because I will have hundreds of probabilities that I have to find.

Distance	Probability
0.33	0.00024266	1/4121=0.00024266
1.2	0.000485319	2/4121=0.000485319
2.08	0.000727979	3/4121=0.000727979
2.71	0.000970638	4/4121=0.000970638
...	...	...
...	...	....
1316.1667	1	4121/4121=1

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