a. 24/91
Explanation:
Calculate first the total number of permutation possible.
You select two socks so that will be:
14⋅13=182
Now you must first select a blue sock then a black sock:
You can only pick 8 possible blue socks
You can only pick 6 possible black socks
which means that this permutation (blue→black) have 8⋅6=48 possibilities for each different blue and black sock.
express in fraction:
48182=2491
