Estimate date

[CD27]

OK, here is a math question which I'm no good at figuring out.

Problem is I would like to create a function that will estimate a date
a certain number is reached based on the number continuing rising.

For example...

160 on 7/1/07

286 7/15/07

500 on 7/25/07

515 on 7/26/07


What is the estimated date 600 will happen?

 

[Harlan Grove]

Problem is I would like to create a function that will estimate a date
a certain number is reached based on the number continuing rising.

For example...

160 on 7/1/07

286 7/15/07

500 on 7/25/07

515 on 7/26/07

What is the estimated date 600 will happen?

Depends. From 7/1 to 7/15 the average daily increase was 9.0, but from 7/15
to 7/25 21.4, from 7/25 to 7/26 15.0. If you want to assume the daily
increase from 7/26 to the date on which it would reach 600 would be the
overall average from 7/1 to 7/26, you could use

=FORECAST(600,--{"7/1/2007";"7/15/2007";"7/25/2007";"7/26/2007"},
{160;286;500;515})

Otherwise, you have way too few data points with which to predict with any
reliability.

 

[CD27]

Thanks for your help! I think I got it.