# How to Find Unknown Value on Excel Graph: 4 Easy Methods

### Method 1 – Using TREND Function

Steps:

• Select the D10 cell and write the following formula,
`=TREND(D5:D9,C5:C9,C10)`
• Hit Enter.

• Have our unknown value and can plot it.

### Method 2 – Applying Trendline Equation

Steps:

• Select the cells containing the known X and Y
• The cells are in the range (C5:D9).
• Go to the Insert tab in the ribbon.
• Choose the Insert Scatter(X,Y) or Bubble Chart command.
• From the drop-down select a scatter plot.
• A chart will be plotted.

• Click the “Plus” sign to the right of the chart.
• Add a trendline by checking the Trendline box.
• Excel will add a trendline to the plot.

• Select any of the data points.
• From there go to the Trendline Options.
• Check the “Display Equation on chart” box.
• The equation of the chart will be shown on the screen.

• Replicate the trendline formula in the D10 cell as follows,
`=2*C10+200`
• Hit Enter.

• We will have an unknown value.

### Method 3 – Applying FORECAST Function.

Steps:

• Select the D10 cell and write the following formula,
`=FORECAST(C10,D5:D9,C5:C9)`
• Hit  Enter.

• Have the unknown value and can plot it on the graph.

### Method 4 – Using GROWTH Function

Steps:

• Start with, choose the D10 cell and write the following formula,
`=GROWTH(D5:D9,C5:C9,C10)`
• Press Enter.

• Get the unknown value and plot it on the graph.

## How to Interpolate in Excel

Steps:

• Choose the G5 cell and write the following formula,
`=D6+(G4-C6)*(D7-D6)/(C7-C6)`
• Hit  Enter.

• Get the interpolated value.

## Related Articles

<< Go Back To Trendline in Excel | Excel Charts | Learn Excel

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