There are 36 possible outcomes when you roll two casino dice and record up-faces in order (first die, second die). fill in the blank: the probability of the sum of the spots on up-faces being 7 is (give your answer to three decimal places.)

Well there are 36 possible outcomes, and  six of these outcomes add up to 7:  1-6, 2-5, 3-4, 4-3, 5-2 and 6-1. So the probability of a particular outcome out of those 36 total outcomes adding up to 7 is 6/36. So the probability of the sum being seven is 6/36 =  16.667%