Percentages Formulas

http://img257.imageshack.us/img257/7738/excelll8.png

Ok, not sure how to explain this properly so here goes;

If you look at that screendump you will see the Days, and then Plant 1,2,3 and the last column showing “% of uptime”.

I need to find the percentage of uptime for each particular Plant per week, if there is 480 minutes in the full daily shift.

Example, Plant 2 shows WEEK TOTAL of 28, so I need to find the weekly percentage, and there is 480mins per day.

Could you help?

thx