Note that 7 represents each of the different 7 regions in the spinner.
1 would represent the red region, as there is one red region.
4 would represent the 4 green regions. Thus, 2 represents the 2 blue regions.
Note that as the spinner spins, no matter which region is colored with which color, the probability of hitting a blue region is
, as out of 7 regions we can hit, 2 are blue.
(Naturally enough, the greater the number of regions of a certain color, the greater the probability of hitting a region of that color.)
7 is the number of the elements in the sample space.
2 is the number of the elements in the event: "hitting blue".
This probability, as mentioned earlier, is matched by the outcome "hitting blue."