Total percentages

[Azza1986]

I want to work out the total percentage of 2 sums,
For example
Matthew worked 5 hours stacking shelfs, in this time he stacked 40 shelves,
his target was to stack 10 shelves per hour so his current percentage would
be 80%.
Matthew then works 3 hours cleaning shelves, in this time he cleaned 45
shelves, his target was to clean 15 shelves per hour so on this job he is
hitting 100%.

What I need to know is what formula I need to use to calculate his overall
percentage for the day, taking into account the duration he spent on each
job????

Thanks to all who maybe of help. Cheers

 

[Luke M]

Assume column A contains hours worked, column B is # of shelves stacked, and
column C is goal per hour. Formula is:
=SUM(B2:B100)/SUMPRODUCT(A2:A100,C2:C100)

 

[Bob Phillips]

Try

=(stacking_achieved+cleaning_achieved)/((stacking_hours*stacking_target_per_hour)+(cleaning_hours*cleaning_target_per_hour))