How to Use the BINOMDIST Function in Microsoft Excel

1. Start Microsoft Excel. You can do this by clicking on Start, highlighting Programs, and clicking Microsoft Excel, or double-clicking the Microsoft Excel icon on your computer's desktop.
2. We just need one cell for this function, so we will use cell A1. Select cell A1. At the top of the screen, click on Insert, and click on Function. Type BINOMDIST in the Search for a function dialog box, click Go, and click OK. Note that you do not want to choose NEGBINOMDIST since it is a separate function. It is the negative binomial distribution, which deals with the probability of a number of failures before a success.As a second possibility, you could select Statistical from the Or select a category drop-down menu, highlight BINOMDIST, and click OK.
3. A dialog box appears, asking you to input the function arguments. Arguments are values used to perform a calculation. The first is Number_s, which is the number of successes in trails. Type 5 here. The second is Trials, which is the number of independent trials. Input 10 here. The third is Probability_s, the probability of a 'success' in each trial. Here, it would be the probability of getting a head, which is .5. The last argument is Cumulative, and you enter TRUE or FALSE here. Since we are interested in the chances of obtaining EXACTLY five heads, enter FALSE. Entering TRUE would give the probability of getting AT MOST five heads.
4. Click OK. The answer, rounded to four decimal places, is .2461. Again, this is the probability of getting EXACTLY five heads on ten flips of a balanced coin.