Probability of rolling a sum of 9 or a sum that is even from two number cubes is 11/18 Explanation: When a dice is rolled there are different ways in which 9. can be obtained, which are (3,6) or (4,5) or (5,4) or (6,3). 4 options. As in all there are 6⋅6=36 options, probability is 4/36 or 1/9.
For getting an even number as sum, we can have (1,1) or (1.3) or (1,5) or (2,2) or (2,4) or (2,6) or (3,1) or (3,3) or (3,5) or (4,2) or (4,4) or (4,6) or (5,1) or (5,3) or (5,5) or (6,2) or (6,4) or (6,6) 18 options, probability is 18/36 or 1/2.
Note that the two events (getting 9 or even sum) are mutually exclusive, the probabilities can be just added i.e. combined probability is 1/9+1/2=2+9/18i.e. 11/18
Well if there is 28 feet, that would be (12x28) 336 inches, and 16 inches between the plug and the first light, there would be only 320 inches left for lights. therefore, if there are 4 inches between each light, we divide 320 by 4. the answer we get is 80. there are 80 lights.
