Calculating overall % estimate

Hi new to the forum, but would appreciate help.

I have a table which has planned hours and an overall estimated % completed. For multiple items how do I find the overall % complete.

.........................Wk 1........Wk 2..............etc etc
Planned .............10...........10
Actual ...............10............0
Estimated %........40%

Planned ..............5............25
Actual ................5.............0
Estimated %........19%

Planned ..............4.............16
Actual ................4..............0
Estimated %.......20%


I need a function which will multiply each estimate by its associated planned hours and then multiply the total planned by the resulting composite %.
ie.70/(20*40%)+(30*19%)+(20*20%) = 0.253.

I have tried various sumif and countif functions but can't get them to work.

As the spreadsheet will be populated by non-excel techies, the function must be able to be copied when new columns and rows are added.

Thanks in advance
Spoed

Thanks for the reply, I don't know where I got the .253 from but it was on my spreadsheet before I erased the calculation, doh.

I shall try your calc unfortunately I cannot rearrange the sheet as I have week1 to week52 and I have planned hours, actual hours and then the estimate for the percentage complete for each week.

Yes the actual divided by planned gives me % complete but some tasks are easy compared to others and the hours do not necessarily reflect the complexity of the task. Estimating % complete is easier than adding in fudge factors.