Yes, the 3 strips together should measure 5". Now is the perfect time to double check your 1/4" seam! Take one of your completed blocks. Using the same ruler you used to cut the strips, measure the middle one. Should measure exactly 1.5". If it is less than that, your seams are too wide. If it's more than 1.5", then it's too narrow. You should also make sure you are cutting accurately and that you are not pressing a tiny crease in the seam when you iron your block.