Question

What is a normal standard deviation for an exam worth 150 points?

Answer 1

>What is a normal standard deviation for an exam?

Depends wildly on the exam.

Some are deliberately set up by the authors to be incredibly good at separating students out by ability, so you get a very high variance. Some are written by people who are incentivised to get most people a 'pass' or similar. Those might have less variance.

That doesn't really matter though...

>I was thinking that seemed very high

Sure. Assuming a normal distribution, that's saying only 70% of people got between 20 and 100 points... which seems like quite a low number for such a large range in my experience. Given the (relatively) low maximum mark, I'd say this sounds like a hard exam (or one the class was not prepared for).

> should I ask my professor to do a curve?

What have you got to lose? If you do it politely and the professor isn't completely unreasonable, I struggle to imagine a world where you get significant backlash for showing concern for your grade.

Answer 2

That does seem like a high variance.  When I teach I shoot for a 1 letter grade variance.

Rather then asking your teacher to curve, maybe ask if they are planning to curve.

Answer 3

There's no question that having the professor grade on a curve is good for *you*, because you'll get a higher grade.

That having been said, I just wanted to put in a word for the professor, whose goal is to teach you a certain collection of concepts and techniques. Let's consider an extreme case: suppose you got the highest grade in the class, but it was only 40 points out of 150. Should you still get an A? I mean, obviously, it would be the professor's fault, if the best student learned such a small piece of the material, but still ... regardless of what grade you get, give the graded exam a good look and figure out what you missed and why. That'll let you really get something out of the exam.