The Envelopes, Big and Small

In front of volunteers were two envelopes, one labelled big and one labelled small. They told the volunteers that there was a ten % chance the envelopes were filled with cash. The volunteers would get to open the envelopes at the end of 20 minutes and pocket the contents. 83 point four percent paid money to effect the timing. You can guess which ones the vollunteers wanted to open.