A further thought ..
Assuming start times in col C, end times in col D
In B1: =SUMPRODUCT((A$1:A$100=C1)*(A$1:A$100<=D1))

Above presumes the start and end times in cols C and D are non-overlapping.

If they are overlapping, eg if in C1:D2 you have:

7:00 AM 8:00 AM
8:00 AM 9:00 AM
etc

just adjust the upper limit, viz use instead in B1:
=SUMPRODUCT((A$1:A$100=C1)*(A$1:A$100<D1))
--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
---