A common width is 36" (x 1 5/8 = 58 1/2", or x 2 = 72") so 3 1/4 yards cut in half and pieced will be just barely larger than your quilt top. This is actually a very efficient use of batting.
For backing, it depends on how much you want around the edges when quilting. If you need 3 or 4 inches on each side, that makes the overall size 64 - 65 wide x 77 - 78 long. This means you will have one seam in your backing, and need either 2 x 65 = 130" (3 5/8 yd) or 2 x 78 = 156" (4 1/3 yd) depending on which way the seam goes.