# How to Use Linear Interpolation in Excel

Linear interpolation is a method used to estimate a value between two known data points. In Excel, this can be achieved by using a simple formula. Follow these steps to perform linear interpolation in Excel:

**Organize your data:**Arrange your data in two columns, with the independent variable (e.g., x-values) in the first column and the dependent variable (e.g., y-values) in the second column. Ensure that the data points are sorted in ascending order.**Identify the interval:**Determine the interval in which the x-value you want to interpolate lies. In other words, find the two data points that surround the desired x-value.**Calculate the slope:**The slope is the rate at which the dependent variable (y) changes with respect to the independent variable (x). To calculate the slope, use the following formula:Slope = (y2 - y1) / (x2 - x1)Here, (x1, y1) and (x2, y2) are the coordinates of the two data points surrounding the desired x-value.**Calculate the interpolated y-value:**Use the following formula to estimate the y-value corresponding to the desired x-value:y = y1 + slope * (desired x-value - x1)**Enter the formula in Excel:**Type the formula into a cell in Excel to calculate the interpolated y-value.

## Example

Let's say we have the following data points:

x | y |
---|---|

1 | 2 |

3 | 4 |

5 | 6 |

7 | 8 |

We want to interpolate the y-value for x = 4.

**Organize your data:**The data is already organized in two columns.**Identify the interval:**The desired x-value (4) lies between the data points (3, 4) and (5, 6).**Calculate the slope:**Use the formula to find the slope:Slope = (6 - 4) / (5 - 3) = 2 / 2 = 1**Calculate the interpolated y-value:**Use the formula to find the interpolated y-value:y = 4 + 1 * (4 - 3) = 4 + 1 = 5**Enter the formula in Excel:**In a cell, type the following formula:`=4 + (1 * (4 - 3))`

Press Enter, and Excel will calculate the interpolated y-value, which is 5 in this case.

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