Not good at math either, but check out this site, it may help. Their version has a few pointed petals, but still all the same width, just different end.
http://www.patternsfromhistory.com/c...en-pattern.htm
Here's one - looks like it has more petals;
http://www.mccallsquilting.com/qb/mc...703/index.html
And one more:
http://www.kathkwilts.com/lessons/plate.html