Randomly chosen 2 students, out of 7 boys, 6 girls; find prob a girl was chosen

I22y60

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Jun 6, 2018
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[FONT=&quot]There are 7 boys and 6 girls in a classroom. The teacher randomly chose 2 kids from the class. What is the probability that a girl was chosen?[/FONT]
 

Jomo

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Dec 30, 2014
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There are 7 boys and 6 girls in a classroom. The teacher randomly chose 2 kids from the class. What is the probability that a girl was chosen?
Hi. In order to receive help you need to tell us where you are stuck. What have you tried? Please share your work with us so we can see where you are going wrong.
 

Dr.Peterson

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Nov 12, 2017
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There are 7 boys and 6 girls in a classroom. The teacher randomly chose 2 kids from the class. What is the probability that a girl was chosen?
There are several ways you might do this, which is part of the reason we ask you to show your own ideas.

One is to first find the probability that neither kid chosen is a girl (that is, two boys are chosen); that's easier than doing it directly. This requires knowing about "and" and "not" in probability.

Another is to find the number of ways to choose 2 kids from the 13, and the number of ways to choose 2 kids, at least one of whom is a girl. Then use the definition of probability. This requires some knowledge of permutations and combinations.

Does either of those sound like something you can do? Give it a try.
 
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