work out % increase

[lavisbre]

Hello

if I get 500 people to a site in a month in position 3
now if i increase it to position 2 I get a 11% increase in traffic
So 500 becomes 785. how do i add that to excel please?


if i move to pos 1 and get a 22 increase in traffic it becomes 1070.
im not good with math and stuck

[alansidman]

Fast answers need visual help. Please read the yellow banner at the top of this page on how to attach a file.

[curiouscat408]

@lavisbre.... Sounds like a class assignment, but oh well....

First, note that 785 is not simply 11% more than 500, which is 500*(1+11%) = 555.

And it is unclear what you mean by "22% increase". From pos 3 (500)? Or from pos 2 (calculated)?

In either case, 1070 is not 22% more than 500, which is 500*(1+22%) = 610. And it is not 22% more than 555 (if that is even correct for pos 2), which is 555*(1+22%) = 677.1.

So I would start by charting the 3 examples, using an XY Scatter chart. See the attached image. Also see the attached Excel file.

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As we can see, the relationship between X and Y appears to be linear.

And in fact, we see in C2:C4 that we can estimate y almost exactly using FORECAST, to wit (in C2):

=FORECAST(A2, $B$2:$B$4, $A$2:$A$4)

So, we can enter any increase factor of the form 1+r (r = 11%, 22%, whatever) into a cell and use FORECAST to determine the number of people resulting from an "r" incease in traffic from that "base" number (500).

Caveat: Arguably, just 3 data points might not be enough to understand the correct relationship between X and Y. IOW, it might not be linear. If you have more data points, and you are still stuck, please post the additional data.

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The form of the linear relationship is est y = a*x + b.

We can array-enter LINEST into E2:F2 (press ctrl+shift+Enter instead of just Enter) to see the coefficients "a" and "b".

They are about 2590.90909 (2590 10/11) and -2909.90909 (-2909 10/11).

(The fraction form can be seen by formatting E2:F2 as Custom "# ?/??" without quotes.)

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[curiouscat408]

PS....

The form of the linear relationship is est y = a*x + b.
[....]
["a" and "b"] are about 2590.90909 (2590 10/11) and -2909.90909 (-2909 10/11).

I chose to use (non-zero) increase factors (1+r) for X just in case the relationship is exponential.

Now that we know it is linear, we can enter the percentage increase in A2:A4 (0, 11%, 22%), and derive the more intuitive linear relationship in E2:F2, namely:

est y = 2590.90909*x + 500

where 2590.90909 is more precisely 2590 10/11.

See the attached image. And see the "Sheet2" worksheet in the attached Excel file.

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