Now that we have received the 2nd block pattern, am looking at the 10 yards of background that will be used. Maybe I missed earlier estimates as to how much fabric to put aside for the borders? Based on the completed size of the quilt - 100 x100 would it be safe to assume we will need 3 1/2 yards for the borders. Sounds like our borders will be about 10" wide? We are getting 4 18" blocks cut from each yard of background x 25 blocks. So I am counting on using the other 6 1/2 yards for the blocks. Math was never my strong suit so hoping you can correct me or confirm. Thanks much.