# Excel 2010

## Using What-If Analysis

### What-if analysis

Excel includes many powerful tools to perform complex mathematical calculations, such as** what-if analysis**. This feature can help you **experiment** and **answer questions** with your data, even when the data is incomplete. In this lesson, you will learn how to use a what-if analysis tool called **Goal Seek**.

### Goal Seek

Whenever you create a formula or function in Excel, you put various parts together to calculate a **result**. ** Goal Seek** works in the opposite way: It lets you start with the **desired result**, and it calculates the **input value** that will give you that result. We'll use a few examples to show how to use Goal Seek.

#### To use Goal Seek (Example 1):

Imagine you're enrolled in a class. You currently have a grade of 65, and you need at least a 70 to pass the class. Luckily, you have one final assignment that might be able to raise your average. You can use Goal Seek to find out **what grade you need on the final assignment** to pass the class.

In the image below, you can see that the grades on the first four assignments are **58, 70, 72, and 60**. Even though we don't know what the fifth grade will be, we can go ahead and write a formula or function that calculates the final grade. In this case, each assignment is weighted equally, so all we have to do is average all five grades by typing **=AVERAGE(B2:B6)**. Once we use Goal Seek, cell **B6** will show us the minimum grade we'll need to make on that assignment.

- Select the cell whose value you wish to change. Whenever you use Goal Seek, you'll need to select a cell that already contains a
**formula**or**function**. In our example, we'll select cell**B7**because it contains the formula**=AVERAGE(B2:B6)**.Selecting cell B7 - From the
**Data**tab, click the**What-If****Analysis**command, then select**Goal Seek**from the drop-down menu.Selecting Goal Seek from the drop-down menu - A dialog box will appear with three fields:
**Set cell:**The cell that will contain the desired result. In our example, cell**B7**is already selected.**To value:**The desired result. In our example, we'll enter**70**because we need to earn at least that to pass the class.**By changing cell:**The cell where Goal Seek will place its answer. In our example, we'll select cell**B6**, because we want to determine the grade we need to earn on the final assignment.

- When you're done, click
**OK**.Entering the desired values into the dialog box and clicking OK - The dialog box will tell you if Goal Seek was able to find a solution. Click
**OK**.Clicking OK - The result will appear in the specified cell. In our example, Goal Seek calculated that we will need to score at least a 90 on the final assignment to earn a passing grade.

The completed Goal Seek and calculated value