Excel Spreadsheet: Discrete ProbabilityALL.xlsx
Another way to download the Excel Workbook is to click here.
How to use the Excel Spreadsheet Provided
To compute the probability of an event using the Excel spreadsheet provided
- First, download the Excel spreadsheet.
- Then click on the Binomial Probability Distrib tab.
- Then enter the sample size in cell B1, and enter the probability of success in cell B2. Hit the Enter key to recalculate the spreadsheet.
Suppose the probability that a customer will purchase your product if they stay more than ten minutes on your website is 0.68. You take a sample of 20 people and you want to know what is the probability that exactly twelve people will make a purchase, P(X = 12).
To compute the probability do the following.
- Enter the sample size (n), 20, in cell B1.
- Enter the probability of success, 0.68, in cell B2.
- Move down column A to x = 12, in cell A16.
- Then move to the right to column B16, 0.1354.
- P(X = 12) = 0.1354.
- In column C, the P(X < 12) is 0.2922. This value is equal to all the probabilities from x = 0 to x=12. Sum the probabilities from cells B5 to B17.
- To determine the mean, variance, and standard deviation, look at cells F1 thru F3.
- The mean is in cell F1, 13.60.
- The variance is in cell F2, 4.352.
- The standard deviation is in cell F3, 2.09.
Suppose you ten people visited Company ABC's website. In the past, 49% of the people who visited the website made a purchase. Determine the following:
- The average number of people who will make a purchase;
- The standard deviation of the people who will make a purchase;
- The probability that exactly five people will make a purchase;
- The likelihood that less than four people made a purchase; and
- Compute the probability that at least six people make a purchase.
First, click the Binomial Probability Distrib. tab at the bottom of the Excel spreadsheet. Note the following.
- Enter 10 in the sample size cell B1 and hit the Enter key.
- Enter 0.49 in the probability of success cell B2 and hit the Enter key.
- To delete a value in a cell, double click the cell and hit the backspace button.
- The average number of people who will make a purchase is in cell F1, 4.90.
- The standard deviation of the people who will make a purchase is in cell F3, 1.58.
- P(X = 5) is in cell B10, 0.2456.
- P(X<4) = P( X < 3) . The cell with the probability is in cell C8, 0.1888.
- P(X > 6) = 1 - P(X < 5). Subtract the value in cell C10, 0.6474 from 1. The value is 1 - 0.6474 = 0.3526
View the video below to see how to use the Excel Spreadsheet provided to compute binomial probabilities.
Video of how to use Excel Spreadsheet