FORECAST

FORECAST(x, known_y's, known_x's)

Returns the future y-value along a linear trend using existing values.

x	The data point for which you want to predict a value.
known_y	The dependent array or range of cells.
known_x	The independent array or range of cells.

REMARKS

* FORECAST.LINEAR was added in Excel 2016 to replace this function.
* If "x" is not numeric, then #VALUE! is returned.
* If "known_y" and "known_x" are empty or contain a different number of data points, then #N/A is returned.
* If the variance of "known_x" equals zero, then #DIV/0! is returned.
* For the Microsoft documentation refer to support.microsoft.com
* For the Google documentation refer to support.google.com

	A
1	=FORECAST(30, {6, 7, 9, 15, 21}, {20, 28, 31, 38, 40}) = 10.607
2	=FORECAST(3.2, 2, 3) = #DIV/0!