In Barcelona during a certain week the average daily rainfall from Sunday to Friday exceeded the average from Monday to Saturday by 16.667%.
The week was on the average just as wet as Sunday.
What was the fall on Saturday?
(In reply to How do we treat evaporation? (spoiler)
by Steve Herman)
The total of 6 days is indeed SU+MO+....FR and it is equivalent to six times the average, i.e. 6y.
Nothing wrong with SH's post.