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4) Best Buddies have 60 students, and 20 students are 12th graders

 

A) What is the probability of 2 students who are 12 graders with replacement?

B) What is the probability of 2 students who are 12 graders without replacement?

C) If 15 random students join Best Buddies, what is the probability that they are 12th graders?

 

asked Feb 21, 2015 in STATISTICS by doan12345 Pupil

2 Answers

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Step 1:

4A)

Total number of students in best buddies are 60.

Among them 20 students are 12th graders.

Out of 60 students 2 students are selected randomly.

Find the probability that the 2 students are from 12th graders.

Assume that the 2 selections are made with replacement.

Let the two events be image.

Probability of selecting first student : .

Probability of selecting second student : .

The two events are independent events then image.

Probability of selecting 2 students is

Probability of selecting 2 students from 60 students who are 12th graders with replacement is 0.1111.

Solution:

Probability of selecting 2 students from 60 students who are 12th graders with replacement is 0.1111.

answered Feb 21, 2015 by Lucy Mentor
edited Feb 21, 2015 by Lucy
0 votes

Step 1:

4B)

Find the probability that the 2 students are from 12th graders.

Assume that the 2 selections are made without replacement.

Let the two events be image.

Probability of selecting first student : .

Probability of selecting second student : .

The two events are independent events then image.

Probability of selecting 2 students is

Probability of selecting 2 students from 60 students who are 12th graders without replacement is 0.1073.

Solution:

Probability of selecting 2 students from 60 students who are 12th graders without replacement is 0.1073.

answered Feb 21, 2015 by Lucy Mentor
edited Feb 21, 2015 by Lucy

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