SOLUTION: A fourth grade class has 22 boys and 9 girls. Their teacher randomly selects two students to return books to the library. Find the probability that the students selected are:

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Question 613367: A fourth grade class has 22 boys and 9 girls. Their teacher randomly selects two students to return books to the library. Find the probability that the students selected are:
a) 2 girls
b) a boy and a girl, in that order
c) a boy and a girl, order being unimportant.
[The answer to "a" is C(9,2)/C(20,2) = .189; that one I see okay. However, I do not see how to calculate either "b" or "c". Your detailed explination is greatly appreciated]. Thank you in advance, Diane
7.4/37
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi, 

A fourth grade class has 22 boys and 9 girls. 31 students in all

P(2girls) = %289%2F31%29%288%2F30%29 = 72/930 = 36/465 = .077

P(boy and then girl) = %2822%2F31%29%289%2F30%29 = 198/930 = 36/465 = .213

P(boy then girl 'or' girl then boy) = .213 + .213 = .426