2. Semiconductor memory devices are made on silicon wafers. The wafer design often includes special built in test circuitry. In the early stages of manufacturing there are often high rates of test failure, which should decrease steadily as design flaws are fixed and manufacturing processes improve. Below is actual data collected for the first twelve wafers of a new, cutting-edge memory chip. Wafer % MBIST fails 1 17.91% 10.00% 3 18.37% 4 19.08% 12.23% 12.35% 3.61% 8 3.25% 9 3.54% 10 8.06% 11 1.38% 12 4.35%