There are 500 students in a high school senior class. Of these 500 students, 300 regularly wear a necklace to

school, 200 regularly wear a ring, and 125 regularly wear a necklace and a ring. Using this information, answer

each of the following questions.

Let N be the event that a randomly selected senior regularly wears a necklace and R be the event that a

randomly selected senior regularly wears a ring.

What is P (N), the probability that a senior wears a necklace?

What is P (R), the probability that a senior wears a ring?

What is P (N and R), the probability that a senior wears a necklace and a ring?

What is P (N or R), the probability that a senior wears a necklace or a ring?

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1. P (N) = 3/5

2. P (R) = 2/5

3. P (N and R) = 1/4

4. P (N or R) = 3/4

Step-by-step explanation:

1. Let's review the information given to us to answer the problem correctly:

Number of students in a high school senior class = 500

Number of students that regularly wear a necklace = 300

Number of students that regularly wear a ring = 200

Number of students that wear a necklace and a ring = 125

2. What is P (N), the probability that a senior wears a necklace?

Let's recall the formula of probability:

Probability = Number of favorable outcomes/Total of possible outcomes

Substituting with the real given values:

P (N) = 300/500 = 3/5 (Dividing by 100 numerator and denominator)

P (N) = 3/5

3. What is P (R), the probability that a senior wears a ring?

Substituting with the real given values:

P (R) = 200/500 = 2/5 (Dividing by 100 numerator and denominator)

P (R) = 2/5

4. What is P (N and R), the probability that a senior wears a necklace and a ring?

Substituting with the real given values:

P (N and R) = 125/500 = 1/4 (Dividing by 125 numerator and denominator)

P (N and R) = 1/4

5. What is P (N or R), the probability that a senior wears a necklace or a ring?

P (N or R) = P (N) + P (R) - P (N and R)

Substituting with the real given values:

P (N or R) = 3/5 + 2/5 - 1/4

P (N or R) = 5/5 - 1/4

P (N or R) = 1 - 1/4

P (N or R) = 3/4