How long will a 2 burner camping stove run on a small propane cylinder?

I got the stove used from a friend. I have no idea what brand it is. it is Grey and black. I am using the coleman 1 # propane cylinders, and I will be camping 3 nights and days will probably use it to make coffee and scrambled eggs each morning. may cook on the campfire most evenings, but may also use the stove one night for dinner as well.