Selective serotonin reuptake inhibitor. Selective serotonin reuptake inhibitors (SSRIs), also known as serotonin-specific reuptake inhibitors or serotonergic antidepressants,[1] are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders.
Then you're looking for the midpoint! The midpoint of a line segment is the point located midway between the endpoints of the line segment. This tutorial tells you about the midpoint of a line segment.
Class Midpoint. The midpoint of each class interval is called the class midpoint and is sometimes referred to as the class mark. It is the value halfway across the class interval and can be calculated as the average of the two class endpoints. Relative frequency is the individual class frequency divided by the total frequency.