2. (4 pts) You work at a fab. Your colleague just mixed up two silicon wafers. Each wafer contains a large number of chip dies. One wafer is bad, 50% of all its dies are faulty. The other is good, only 10% are faulty. Testing is expensive. You randomly pick one wafer, then randomly test 4 dies. Only one turns out faulty. Is the wafer good or bad? Give the decision that would minimize your chances of being wrong