Extrapolating a future value using two values

[PJ0302917]

[TABLE="width: 300"]
<tbody>[TR]
[TD]Day
[/TD]
[TD]Price
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD]1.0
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD]5.0
[/TD]
[/TR]
[TR]
[TD]4
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]5
[/TD]
[TD]10.0
[/TD]
[/TR]
</tbody>[/TABLE]
Hi

I'm trying to calculate a future value based on a trend line calculated off two values.

I've tried searching example/tutorials and can only find where the data is fully populated.

I'd like to use something like the trend() to predict a value on day 20?

I'd really appreciate it if someone could point me in the right direction.

Thanks

 

[Gerald Higgins]

OK, given your sample data, what should the result be on day 20 ?

 

[PJ0302917]

Sorry I should have used a better sample data set, I’m looking at a linear trend line so maybe the dataset should have days 1 -20 and the corresponding values are 1-20


So day 6’s value = 6
Day 20’s value = 20

How can I work out day 25? Based on the trend line from the two values above? The answer will be 25

Thanks

 

[joeu2004]

I’m looking at a linear trend line [....]
So day 6’s value = 6
Day 20’s value = 20
How can I work out day 25? Based on the trend line from the two values above? The answer will be 25

Use the FORECAST function. But you have provided very different data; the first has 3 pairs of values, not just 2. So I'm confused.

Suppose that A1:A6 contain the day numbers 1,3,5,6,20,25. And B1:B5 contain the corresponding values that you posted, namely: 1,5,10,6(!),20.

Then the estimated values might be calculated in one of 3 ways, depending on your intent (which I'm confused about).

1. Based on the original 3 data pairs. Enter the following into C1 and copy down through C6:

=FORECAST(A1,$B$1:$B$3,$A$1:$A$3)

2. Based on 5 data pairs: the original 3 and the additional 2. Enter the following into D1 and copy down through D6:

=FORECAST(A1,$B$1:$B$5,$A$1:$A$5)

3. Based on just the last 2 data pairs. Enter the following into E1 and copy down through E6:

=FORECAST(A1,$B$4:$B$5,$A$4:$A$5)

 

[PJ0302917]

Thanks joeu2004

Your first example worked perfectly, thank you for taking to time to help and get me up and running with the FORECAST function.