# What do you call just the first half of a bell curve?

What do you call a curve that is just the first half of a bell curve. For example, let's say in a typical bell curve of letter grades, a few students get F grades most get C grades and just a few get A grades.

I'd like a curve that is the first half of the bell curve so that a few students get F grades and the most common grade is an A grade.

(I'm not actually doing this for grading. It's just the example that came to mind.)

• what kind of answer you are expecting? The first half of a bell curve is the first half of the bell curve. Even if it had specific name, I do not understand how would that might help. Mar 21, 2011 at 8:18
• if we take first half of a bell curve, then we truncate the original distribution. So truncated normal distribution might be something you are after. Mar 21, 2011 at 8:23
• The shape you describe can be variously described as 'sigmoid'. Is this what you are after? It is quite unclear what this question is about (specially because the sample is a discrete distribution with three values only, which can be equally called triangular instead of bell-shaped). Aug 27, 2023 at 16:33