SOLUTION: _____Five juniors and four seniors have applied for two open student council positions. School administrators have decided to pick the two new members randomly. What is the probabi

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: _____Five juniors and four seniors have applied for two open student council positions. School administrators have decided to pick the two new members randomly. What is the probabi      Log On


   

Question 935405: _____Five juniors and four seniors have applied for two open student council positions. School administrators have decided to pick the two new members randomly. What is the probability they are both juniors or both seniors ?
A) 0.722 B) 0.395 C) 0.569 D) 0.444 E) 0.506
*Could you please tell me step by step how to get the answer to the problem? Thank You so much for helping me !! :)
Answer by Edwin McCravy(20081) About Me  (Show Source):
You can put this solution on YOUR website!
%22P%28both_juniors%29%22+=+%22C%285%2C2%29%22%2F%22C%289%2C2%29%22+=+10%2F36=5%2F18

%22P%28both_seniors%29%22+=+%22C%284%2C2%29%22%2F%22C%289%2C2%29%22+=+6%2F36=1%2F6

Since the event of being a junior and the event of being a senior
are mutually exclusive, we can add the probabilities:

%22P%28both_juniors_OR_both_seniors%29%22+=+5%2F18%2B1%2F6=5%2F18%2B3%2F18=8%2F18=4%2F9

Edwin