There are 9 people in the room. There are two pairs of siblings within that group. If we choose two people, what is the probability that they will not be siblings?
Choose the correct option.
A) 12/18	B) 17/18	C) 2/9	D) 1/18	E) 4/18
we have XXXXXBBCC   We have to take into the account when we have XX, XB, XC   So 5/9*4/8 5/9*2/8 and 5/9*2/8 note we need to multiply these by 2 (except the first) b/c we can have BX and CX.   20+20+20 --&gt; 60/72 --&gt; 30/36 --&gt; 15/18   then next is   17/18C 2/9*2/8 --&gt; 4/72 2/36 1/18 --&gt; multiply this by 2 b/c of C17/18   so 2/18+15/18 --&gt; 17/18   ANSWER:17/18
<result>B</result>
There are 9 people in the room. There are two pairs of siblings within that group. If we choose two people, what is the probability that they will not be siblings?