I thought I made it very clear when I said "I send out a total of 30 fast and 3 slow Explorers each day". Let me spell it out in case anyone is confused still by this...
I send 15 Fast Explorers out in the morning. Those 15 Fast Explorers return after about 10.5 hours. I then send them out again in the evening of SAME DAY along with the 3 slow ones. That equals 30 Fast Explorers each day + 3 slow. In case anyone is a new player, the Slow Explorers are purchased from Tavern. The Fast Explorers come from Merchant using gems or from Events.
The point of my post was to show odds by giving total that went out and how many scenarios were earned. The details of how I did it is just bonus info in case it is of value to anyone.