Percentage of Correct Records

[rrstudio2]

I have a spreadsheet like:

Lot Slot Cars Tagged Properly
A 1 2 1
B 1 10 10
A 2 5 4
B 2 1 1
C 3 3 2

I have about 400 rows of this type of data. Basically I want to
generate some graphs showing the percent of cars properly tagged per
lot:

Lot Properly Tagged
A 71%
B 100%
C 66%

What is the best way to do this? I tried a pivot table and I can get
a sum of the cars per lot and a sum of the properly tagged cars in
that lot, but can't make it do a percentage. Is there a formula I
could use for this OR would there be a better way to record this data
in the future?

Thanks,
Andrew V. Romero

 

[Bill Kuunders]

=SUMPRODUCT((A3:A400="A")*(D3400))/SUMPRODUCT((A3:A400="A")*(C3:C400))
format cell as percentage