Use the image to answer the question.

A Venn diagram shows two intersecting circles. Circle 1 represents event A, 3 and 5. Circle 2 represents event B, 6, 8, 10, and 12. The intersection of both the circles is labeled 7, 9, and 11. The space outside the circles is labeled 2 and 4.

The Venn diagram represents the results of the experiment of rolling two fair, six-sided number cubes and adding the sum of the two rolls. Consider event A as “sum is odd” and event B as “sum is 6 or greater.” Find the probability that the sum is odd, given that the sum is 6 or greater.

(1 point)
Responses

312
Start Fraction 3 over 12 End Fraction

35
Start Fraction 3 over 5 End Fraction

512
Start Fraction 5 over 12 End Fraction

37

1 answer

To find the probability that the sum is odd given that the sum is 6 or greater, we can apply the formula for conditional probability:

\[ P(A|B) = \frac{P(A \cap B)}{P(B)} \]

Where:

  • \( P(A|B) \) is the probability of event A occurring given that event B has occurred.
  • \( P(A \cap B) \) is the probability of both events A and B occurring.
  • \( P(B) \) is the probability of event B occurring.

Step 1: Identify the outcomes.

When rolling two six-sided dice, the possible sums can be from 2 to 12. The outcomes are:

  • Sums that are odd: 3, 5, 7, 9, and 11 (so, A = {3, 5, 7, 9, 11}).
  • Sums that are 6 or greater: 6, 7, 8, 9, 10, 11, and 12 (so, B = {6, 7, 8, 9, 10, 11, 12}).

Step 2: Find \( A \cap B \) (i.e., outcomes that are both odd and 6 or greater).

  • The odd sums that are 6 or greater are: 7, 9, and 11. So, \( A \cap B = {7, 9, 11} \).

Step 3: Count the outcomes.

  • The number of successful outcomes for \( A \cap B \) is 3 (the sums 7, 9, and 11).
  • The total outcomes for event B (sums that are 6 or greater) is 7 (the sums 6, 7, 8, 9, 10, 11, and 12).

Step 4: Calculate the probabilities.

  • \( P(A \cap B) = \frac{3}{12} \) since there are a total of 12 possible outcomes when rolling two dice (ranging from 2 to 12).
  • \( P(B) = \frac{7}{12} \) since there are 7 outcomes that are 6 or higher.

Step 5: Calculate \( P(A|B) \).

Using the conditional probability formula:

\[ P(A|B) = \frac{P(A \cap B)}{P(B)} = \frac{\frac{3}{12}}{\frac{7}{12}} = \frac{3}{7} \]

So the answer is:

\(\frac{3}{7}\)

Thus, the correct response is:

37