How do I interpolate numbers in Excel?

[Help!!!!!]

I was trying to interpolate numbers by using Forecast, but it is not the
linear interpolation result I need. I am wondering is there a way to do it?

Following is Forecast help example. By using Forecast, the result is 10.6,
but if using interpolation, Known Y (7,9) Known X (28,31), the result should
be 8.333

Known Y KnownX
6 20
7 28
9 31
15 38
21 40
Formula Description (Result)
=FORECAST(30,A2:A6,B2:B6) Predicts a value for y given an x value of 30
(10.60725)

Thank you very much in advance !!!!!!

[Niek Otten]

I think you are confusing Y and X

--
Kind regards,

Niek Otten

"Help!!!!!" <Help!!!!!@discussions.microsoft.com> wrote in message news:EBDC4DBF-3559-4D5E-8C4D-160F2FBE068D@microsoft.com...
>I was trying to interpolate numbers by using Forecast, but it is not the
> linear interpolation result I need. I am wondering is there a way to do it?
>
> Following is Forecast help example. By using Forecast, the result is 10.6,
> but if using interpolation, Known Y (7,9) Known X (28,31), the result should
> be 8.333
>
> Known Y KnownX
> 6 20
> 7 28
> 9 31
> 15 38
> 21 40
> Formula Description (Result)
> =FORECAST(30,A2:A6,B2:B6) Predicts a value for y given an x value of 30
> (10.60725)
>
> Thank you very much in advance !!!!!!

[Mike Middleton]

The example fits a straight line using all five values and bases the
forecast on that fitted line.

For interpolation between two points, use only the two adjacent values for
the straight-line forecast:

=FORECAST(30,A3:A4,B3:B4)

or

=FORECAST(30,{7,9},{28,31})

and the result is 8.3333.

- Mike
www.mikemiddleton.com

"Help!!!!!" <Help!!!!!@discussions.microsoft.com> wrote in message
news:EBDC4DBF-3559-4D5E-8C4D-160F2FBE068D@microsoft.com...
>I was trying to interpolate numbers by using Forecast, but it is not the
> linear interpolation result I need. I am wondering is there a way to do
> it?
>
> Following is Forecast help example. By using Forecast, the result is
> 10.6,
> but if using interpolation, Known Y (7,9) Known X (28,31), the result
> should
> be 8.333
>
> Known Y KnownX
> 6 20
> 7 28
> 9 31
> 15 38
> 21 40
> Formula Description (Result)
> =FORECAST(30,A2:A6,B2:B6) Predicts a value for y given an x value of 30
> (10.60725)
>
> Thank you very much in advance !!!!!!

[Bruce Sinclair]

In article <EBDC4DBF-3559-4D5E-8C4D-160F2FBE068D@microsoft.com>, =?Utf-8?B?SGVscCEhISEh?= <Help!!!!!@discussions.microsoft.com> wrote:
>I was trying to interpolate numbers by using Forecast, but it is not the
>linear interpolation result I need. I am wondering is there a way to do it?
>
>Following is Forecast help example. By using Forecast, the result is 10.6,
>but if using interpolation, Known Y (7,9) Known X (28,31), the result should
>be 8.333
>
>Known Y KnownX
>6 20
>7 28
>9 31
>15 38
>21 40
>Formula Description (Result)
>=FORECAST(30,A2:A6,B2:B6) Predicts a value for y given an x value of 30
>(10.60725)
>
>Thank you very much in advance !!!!!!

You could use the slope and intercept functions and calculate the numbers
you ned using those. That way the function doesn't get in the way of what
you are trying to do


Bruce

----------------------------------------
I believe you find life such a problem because you think there are the good
people and the bad people. You're wrong, of course. There are, always and
only, the bad people, but some of them are on opposite sides.

Lord Vetinari in Guards ! Guards ! - Terry Pratchett

Caution ===== followups may have been changed to relevant groups
(if there were any)

[gjcase]

You can plot the data & insert a non-linear trendline, using the option to display the quation on the chart, then use that equation to back out your intermediate values.

---GJC