Question

Please help. A spinner had 7 identical sections. Two sections are blue, 1 us red, and 4 of the sections are green. Suppose the probabilty of an event happening is 2/7 (fraction). What does each number in the ratio represent? What outcome matches this probability?

Answer 1

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 $\displaystyle{ \frac{2}{7}$, 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."