Calculations don't compute...

[Guest]

Here's what I have...

A1 B1 C1
16.16 =((c1-a1)/2)+a1 24.44

Which, of course, gives us the value of 20.3 in cell B1, which is the
mid-point between the values in cells A1 and C1. However, why do I get
different percentages when I calculate a1/b1 and b1/c1? Shouldn't the
percentage be the same if the difference between the numbers is the same?

Thanx.

 

[Raffael]

Well, it shouldn't...

1/10 is different from 91/100, right? The difference between them is the
same (9), and so is the percentage...

Regards!

 

[David Biddulph]

You would get the same percentage if B1 was the geometric mean of A1 and C1,
but you've got the arithmetic mean.

You can get the geometric mean by
=SQRT(A1*C1) or =(A1*C1)^0.5 or =GEOMEAN(A1,C1)

You will, I hope, realise that your arithmetic mean could have been
calculated, rather than =((C1-A1)/2+A1), as
=(A1+C1)/2 or as AVERAGE(A1,C1)