How can I calculate total per hour using data in a number cell and one in a
custome cell hh:mm:ss?

For example:
A1 54 emails completed
A2 00:11:22 Avg per email
A3 10.23 Emails per hour

Normally I would have to use the following equation:
11*60=660+22=682secs*54=36828sec/60=613.8min/60=10.23per hour

How can I get excel to read cell A1 and A2 and calculate A3?