Everybody knows the average length of the penis. What is the standard deviation of the penis? IE how spread out are the numbers and what would the distribution be? I know this is stupid, but it just popped into my head. For example: My professsor gave our tests back and said the avg was 65 witha a standard deviation of 27. That means half of the class did really well and the other half didnt. If he said the standard deviation was 5, then the majority of the tests would lie in around 60-70.