I am working on a schedule where there are many different workers, and many
different shifts of different lengths are being used. I have been trying to
create a formula that sums the total hours for each person, based on the name
in the adjacent column. For example:

A B C
4-8pm Mark 4.00
6-8pm Dave 2.00
8pm-11pm Mark 3.00

My hope is that there is some conditional formatting to say if column B =
"Mark", sum the amounts adjacent to the name Mark in column C, to the output
value would be 7.00 hours.