MA,
Arrange a table in the following manner:

Time In Time Out 8:00 9:00 10:00 11:00
7:15 10:19 1 1 1 0
5:02 9:26 1 1 0 0
8:35 12:00 0 1 1 1
Sums 2 3 2 1

Put time marks (hours) into the head row.
Put Excel functions like
=If(And(C$4$A5,C$4<$B5),1,0)
by proper copying into the cells where you see 1s and 0s here as the
results.
Make the histogram as a bar chart, using rows: hours (as cathegories) and
sums (as values).
You are free to modify the shape of the recommended function as to the
affiliation to individual time intervals (is he/she present within an hour,
if spends one or 31 minutes? etc.).
Regards

--
Petr Bezucha


"MA" wrote:

My data is like this:
PersonID Date TimeIn TimeOut
1 1/1/2008 03:18 05:18
2 1/1/2008 11:19 14:21
3 1/3/2008 09:27 15:29

I would like to make a chart that shows how many people were present for
each hour of the day (1 to 24)

Thanks
MA