Working out Percentage needed in quality checks to hit average target

[smattless]

Hello guys

I'm new to excel and this site but have learnt so much already so thanks for all the free info!!

Now what i'm trying to do is work out:

If say "Dave" has 6 quality checks in a month and he gets 90%,90%,90% and finally 20%. He has 2 checks left that month. what is the average he needs to hit (%) to achieve target of 90% average.

Is there a way in excel to calculate the average needed to hit target?

Many thanks

[benishiryo]

welcome to the forum. this is more like a maths question. say your data is:
Data Range
Data Range

	A	B	C	D
1	90%		Target	90%
2	90%		Ave:	125%
3	90%
4	20%
5
6

in D1:
=(D1*6-SUM(A1:A6))/MAX(COUNTBLANK(A1:A6),1)

[smattless]

Many thanks benishiryo

Had to modify it a bit as number of checks can change and targets but all working now!!! cheers again