Dynamic Ranking Column based on other column data

lurking

I am putting together some results from a marathon running event. With these events there is typically the "overall" winner and ranking and then age group winners, generally divided into male/female. So for example, a person may have come in 50th for the entire race, but in second place for "Females, ages 40-49".

What I am looking to do is to create a dynamic "ranking" column that is based on another column in my table that displays each runner's actual finish time. So if I have 100 people listed, the dynamic ranking column would show in proper order what place people came in from 1 - 100 based on their finish time (finish time is a column). Then, if the table were filtered to e.g. only show the 50 females who participated (gender is a column), the dynamic ranking column would update to show places 1 - 50 based on finish times. Same idea for the age groups- if the table were filtered to show the five females in the age 40-49 age group, the ranking column would display places 1 - 5 based on the finish time column.

I am totally unsure what the correct approach is to create or use this functionality- any ideas and assistance is greatly appreciated... thanks!