3.5 Geometric Probability Distribution using Excel Spreadsheet
- Page ID
- 22446
How to use Excel function for Geometric
Suppose the probability that a red car enters an intersection is 0.24. What is the likelihood that the first red car enters the intersection after four non-red vehicles pass through the intersection? The discrete probability distribution is Geometric.
P(Red Car) = .24
P(Not Red Car) = 1-.24 = .76
P( X = 5) = (.76)4(.24) = 0.0801 Rounded to 4 decimal places
To compute the probability in an Excel spreadsheet, enter the formula below.
=NEGBINOM.DIST(4, 1, 0.24, FALSE)
- 4 represents the four non-red cars that have entered the intersection before the red car.
- 1 represents the first red car that enters the intersection.
- 0.24 is the probability of a red car entering the intersection.
- False means you want to compute a probability for one value, P(X = 5).
- True means you want to compute the P(X < 5).
The answer you should see is 0.080069. Rounded to four decimal
You can also enter the following formula for one probability
= (.76^4)*.24
To make sure the formula is calculated, hit the Enter key after entering the formula.
Interactive Element: Live Excel Spreadsheet
Example \(\PageIndex{1}\)
Next, find the probability that at most 4 white cars pass through the intersection during one hour.
Solution
The probability statement is P(X < 4). The Excel function is =NEGBINOM.DIST(3, 1, 0.24, True) . The answer is 0.6664 rounded to 4 decimal places.