Question 852708
<pre>
Let these 13 blanks represents the seats:

_ _ _ _ _ _ _ _ _ _ _ _ _


We calculate the number of ways this can happen,
with the other 11 people seated between the boys. 

<u>B</u> _ _ _ _ _ _ _ _ _ _ _ <u>B</u>

and then we'll divide by 13!, the number of ways 
anybody can sit anywhere.

For 

<u>B</u> _ _ _ _ _ _ _ _ _ _ _ <u>B</u>

we choose the boy on the left in 7 ways and the boy on the right
in 6 ways, and the 11 remaining people in the middle in 11! ways.

So that's 7󬝭1! successful ways, with boys on each end.

Now we'll divide that by 13!

{{{7*6*11!/13!}}}{{{""=""}}}{{{7/26}}}

Edwin</pre>