Use the following situtation to answer the questions: At the library, there are 50 books on a shelf. There are 8 romance novels, 12 historical fiction novels, 15 mystery novels and 15 nonfiction books. Ravi must choose 2 books and doesn't really care which kind they are. He decides to randomly pick 1 and then pick another without replacement.



Question 1
What is the probability of selecting a historical fiction book and then a romance novel?(1 point)
Responses

1250×850
12 over 50 times 8 over 50

1250×849
12 over 50 times 8 over 49

850
8 over 50

1250
12 over 50
Question 2
What is the probability that he pics a nonfiction book and then a mystery novel?(1 point)
Responses

1550
15 over 50

1550×1550
15 over 50 times 15 over 50

1550×1549
15 over 50 times 15 over 49

1549
15 over 49

1 answer

To answer each question, we'll calculate the probabilities based on Ravi's selections without replacement.

Question 1: What is the probability of selecting a historical fiction book and then a romance novel?

  1. Probability of selecting a historical fiction book first:

    • There are 12 historical fiction books out of 50 total books.
    • Probability = \( \frac{12}{50} \)
  2. After selecting one historical fiction book, 49 books remain, and there are still 8 romance novels.

    • Probability of selecting a romance novel second = \( \frac{8}{49} \)

The combined probability for both events (historical fiction first, then romance) is: \[ \frac{12}{50} \times \frac{8}{49} = \frac{12 \times 8}{50 \times 49} = \frac{96}{2450} \] The correct response is: \[ \frac{12}{50} \times \frac{8}{49} \]

Question 2: What is the probability that he picks a nonfiction book and then a mystery novel?

  1. Probability of selecting a nonfiction book first:

    • There are 15 nonfiction books out of 50 total books.
    • Probability = \( \frac{15}{50} \)
  2. After selecting one nonfiction book, 49 books remain, and there are still 15 mystery novels.

    • Probability of selecting a mystery novel second = \( \frac{15}{49} \)

The combined probability for both events (nonfiction first, then mystery) is: \[ \frac{15}{50} \times \frac{15}{49} = \frac{15 \times 15}{50 \times 49} = \frac{225}{2450} \] The correct response is: \[ \frac{15}{50} \times \frac{15}{49} \]

Through the calculations, the correct answers to the questions are:

  1. \( \frac{12}{50} \times \frac{8}{49} \) for Question 1
  2. \( \frac{15}{50} \times \frac{15}{49} \) for Question 2