The way I figure you can get 8 (4 3/4") squares by WOF and 15 by LOF for 2 yards so that would make 120 (4 3/4") squares of the light fabric. (You need 4 light squares per block and want 30 blocks, therefore 120 light squares.)
The dark fabric 8 (4 3/4") squares by WOF and 18 by LOF for 2 1/2 yards would only give you 144 squares (see below for correction) rather than the 150 squares needed. (You need 5 dark squares per block and want 30 blocks, therefore 150 dark squares.)
WOF -- 40 divided by 4.75 = 8.421052632
LOF -- Light 72 divided by 4.75 = 15.15789474
LOF -- Dark 90 divided by 4.75 = 18.94736842
LOF -- Dark 84 divided by 4.75 = 17.68421053
Available Light squares of fabric 8 x 15 = 120 needed 4 x 30 =120
Available Dark squares of fabric 8 x 18 = 144 needed 5 x 30 = 150
Available Dark squares of fabric 8 x 17 = 136 needed 5 x 30 = 150
Janey - Neat people never make the exciting discoveries I do.
ETA the figures are based on the fact that the fabric is square, but there is a very slight wiggle room.
Last edited by OurWorkbench; 11-29-2020 at 06:50 PM.
Reason: correction figures based on new measurements