Teresa and Julia are among 10 students who have applied

Jace Baxter

Jace Baxter

Answered question

2022-02-12

Teresa and Julia are among 10 students who have applied for a trip to Washington, D.C. Two students from the group will be selected at random for the trip. What is the probability that Teresa and Julia will be the 2 students selected?

Answer & Explanation

lofia1r

lofia1r

Beginner2022-02-13Added 15 answers

For this question, we're looking at the number of ways we can satisfy a certain condition (having Teresa and Julia be picked) over the number of ways a group of 2 students can be picked.
Since we don't care in what order people are picked, we're working with combinations, where the general formula is:
Cn,k=n!(k!)(nk)! with n=population,k=picks
How many ways can 2 people be picked from a group of 10?
C10,2=10!(2!)(102)!=10!(2!)(8!)=10×9×8!2×8!=45
There's only one combination that allows Teresa and Julia to be picked.
Putting it together, we have 145

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