Default meeting length in Resource Reservations DB

Hi-Does anyone know how to specify the default meeting length in Resource Reservations? Ours is set to 1/2 hour and I want it to be 1 hour. In other words, if I enter the meeting start time as 9:00 AM the system automatically enters 9:30 AM into the end time field. I want it to enter 10:00 AM.

Thanks for any help.

-Nate Greene