Excel’s binomial distribution function, is a good example of how Excel can make complex calculations easier.

 

 

 

Probability calculations, like those involving the binomial distribution, can be difficult and tedious to perform manually. With Excel 2003 you can perform complex statistical calculations like this with just a few simple steps.

 

The binomial distribution function is used to calculate the probability of a certain number of events, in a given number of trials. For example, you could use this function to find the probability of getting exactly three heads, in 10 tosses of a fair coin.

 

In the example worksheet shown above, the event of getting heads has been assigned a probability of .5, (fifty/fifty chance for a single toss). To find the chances of getting exactly one head (no more or no less) in 10 tosses, we should use the BINOMDIST function.

 

 To start, you would select cell E3 and invoke the insert function dialogue box by clicking the function button next to the formula bar, or by selecting Insert->Function from the menu bar.

 

 The next step is to select the BINOMDIST function from the statistical category and click OK. When the function arguments box is displayed, click the first argument field in the box (Number_s) and then click on cell C3 to enter the number of successes we are looking for (one in this case).

 

To continue, you would click the next argument field, Trials, and then click the cell representing the number of coin tosses D3. Next, you would select the Probability argument field, and click cell B3 to assign a probability of .5 to the function. In the final Cumulative argument field, you would type false, because we want the chances of getting exactly one head (no more or no less).

 

After you enter your selections, the Function Arguments box should look like this. You can see that the probability of getting exactly one head in 10 tosses of a fair coin is around .00976. Clicking OK would make this result visible in cell E3.

 

Once you have a result in E3, you can AutoFill down to E12 and the function will calculate the probabilities accordingly for each cell in the column.

 

 

This demonstrates how you can perform multiple complex calculations easily, by using a built in function and the AutoFill feature.