A class has 11 boys, 9 girls. Two students will be selected at random to serve on committee. What's probability that both will be girls?

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hala718's profile pic

hala718 | High School Teacher | (Level 1) Educator Emeritus

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Given that the number of boys and girls in a class is as follows:

Number of boys = 11

Number of girls = 9

Then we conclude that the total number of students in the class= 20 students.

Then, the probability of choosing a girl = number of girls. total number of students in the class = 9/20

The probability of choosing the 2nd girl = number of remaining girls / number of all students minus the chosen girl = 8/19

Then , the probability of choosing two girls is :

The probability of choosing 2 girls = 9/20 *  8 /19

                                                 = 72/380

                                                 = 18/ 95

Then the probability of choosing 2 girls = 18/95                                     

crystaltu001's profile pic

crystaltu001 | Student, Grade 10 | (Level 1) Valedictorian

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There are 9 girls and 11 boys. You first add them together to get the total and 9 + 11 is 20. The probability that it will be girls is a 9/20

nisarg's profile pic

nisarg | Student, Grade 11 | (Level 1) Valedictorian

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`9/20*8/19=72/380=18/95`

girls to class then girls-1 to class-1 multiplied gives you the chances of that happening

neela's profile pic

neela | High School Teacher | (Level 3) Valedictorian

Posted on

There are 11 boys and 9 girls. To find the probability of randomly selecting two students who are both girls.

There are 11+9 = 20 students.Two students can be randomly selected from 20 in 20C2 = 20*19/2 = 190 ways.

Since the there are 9 girls , the number of ways of selecting the girls from 9 students = 9C2 = 9*8/2 = 36.

Therefore the probability that the sected two students are grls for the committee is 36/190 = 18/95.

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