Xander spends most of his time with his 10 closest friends. he has known 4 of his 10 friends since kindergarten. if he is going to see a movie tonight with 3 of his 10 closest friends, what is the probability that the first 2 of the friends to show up to the movie are friends he has known since kindergarten but the third is not? a. 1/10 b. 12/125 c. 9/125 d. 1/30

This is like the equivalent to a jar with 4 green balls and 6 white balls, where you are picking 3. (The 4 green balls signify the friends from kindergarten.) 

You want to solve the probability that the first two balls are green and the third is white. 
First draw --> 4 green out of 10 balls --> 4/10 = 2/5 

Second draw --> 3 green out of 9 balls --> 3/9 = 1/3 

Third draw --> 6 white out of 8 balls --> 6/8 = 3/4 

2/5 x 1/3 x 3/4 

= 6/60 

= 1/10 

so the answer is 1/10 (or 10%)