Calculating a percentage with the end percentage in mind

[Shadowshady]

I need to create a formula that will calculate percentage needed to reach a
determined percentage at the end of the month.

For example,
week 1 = 14%
Week 2 = 13.2%
Week 3 = ?
Week 4 = ?

Month End Goal 13.8%

Is there a way to calculate what percentage is needed for week 3 and 4 to
acheive the goal?

Thanks, Noah

 

[Mallycat]

It is best to do this type of thing using the original numbers, not the
percentages. Work out the balance needed to make the total for the
month then divide it by the number of weeks left, and calculate the %
from there.

Matt

 

[Bob Phillips]

If you put in

=3*13.8%-SUM(A1:A2)

in the third cell, and

=4*13.8%-SUM(A1:A3)

in the fourth cell, that should doi it. At first the 4th cell will show
13.8%, as the third will make all the correction, but when you overtype that
with the achieved value, the fourth will adjust.

--
HTH

Bob Phillips

(replace somewhere in email address with gmail if mailing direct)