A gynecologist mechanic?

A gynecologist had a burning desire to change careers and become a mechanic. So she found out from her local tech college what was involved, signed up for evening classes and attended diligently, learning all she could. When time for the practical exam approached, she prepared carefully for weeks, and completed the exam with tremendous skill. When the results came back, she was surprised to find that she had obtained a mark of 150%. Fearing an error, she called the instructor, saying "I don't want to appear ungrateful for such an outstanding result, but I wondered if there had been an error which needed adjusting." The instructor said, "During the exam, you took the engine apart perfectly, which was worth 50% of the total mark. You put the engine back together again perfectly, which is also worth 50% of the mark. I gave you an extra 50% because you did all of it THROUGH the muffler..."