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(Find the Probability Question)

Choose 2 girls from a class of 12 boys and 8 girls.

1 Answer

11 votes

Explanation:

what should be the question ?

how many different pairs of 2 girls can you pick out of 8 ?

what is the probability that a specific girl is in the picked pair ?

or is it : if you pick randomly 2 students from the class, what is the probability to have picked 2 girls ?

and there are more options.

but I assume the problem is the picking randomly 2 students.

so, it is 20 students (12 + 8). if we pick 1 student, we have a chance of 12/20 = 3/5 to pick a boy, and a chance of 8/20 = 2/5 to pick a girl.

in our experiment we pick 2 students in a row without returning the first pick into the main pool.

the probabilty for the first pick to be a girl is, as mentioned, 2/5 or 0.4.

for the second pick we have only 7 out of 19 choices to pick a girl. so, the probability to pick a girl now is 7/19.

the combination of both (non-overlapping) probabilities is done via multiplication, and the probabilty to pick 2 girls is :

2/5 × 7/19 = 2×7 / 5×19 = 14/95 = 0.147368421...

User Dpant
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