Question 935405
<pre>
{{{"P(both_juniors)" = "C(5,2)"/"C(9,2)" = 10/36=5/18}}}

{{{"P(both_seniors)" = "C(4,2)"/"C(9,2)" = 6/36=1/6}}}

Since the event of being a junior and the event of being a senior
are mutually exclusive, we can add the probabilities:

{{{"P(both_juniors_OR_both_seniors)" = 5/18+1/6=5/18+3/18=8/18=4/9}}}

Edwin</pre>