Question 1041970:  Five students will be randomly selected from the seven top students in mathematics to represent their school in a regional competition. Angela (A) and Brian (B) are among the seven students, and they wish to determine the probability that they will both be chosen. Using A, B, C, D, E, F, and G to denote the students, set up a sample space to determine this probability. What is the probability they will both be chosen? Enter probability as a fraction. 
 Answer by Fombitz(32388)      (Show Source): 
You can  put this solution on YOUR website! Look at the number of possible choices that contain both A and B, that leaves 3 choices to pick out of a pool of 5. 
  
For the sample space, look at all possible 3 pick choices not including A and B. 
ABCDE, ABCDF, ABCDG 
ABCEF, ABCEG 
ABCFG 
ABDEF, ABDEG 
ABDFG 
ABEFG 
Look at the total number of possible choices, 5 choices out of a pool of 7. 
  
So then the probability would be, 
  
ABCDE, ABCDF, ABCDG, ABCEF, ABCEG, ABCFG 
ABDEF, ABDEG, ABDFG 
ABEFG 
ACDEF, ACDEG, ACDFG,  
ACEFG 
ADEFG 
BCDEF, BCDEG, BCDFG 
BCEFG 
BDEFG 
CDEFG 
 
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