Suppose a math class contains 41 students, 19 females (two of whom speak French) and 22 males (three of whom speak French). Compute the probability that a randomly selected student is male, given that the student speaks French.

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**Problem Statement: Conditional Probability**

Suppose a math class contains 41 students, 19 females (two of whom speak French) and 22 males (three of whom speak French). Compute the probability that a randomly selected student is male, given that the student speaks French.

**Solution:**

Let:
- F denote the event that a student is female.
- M denote the event that a student is male.
- S denote the event that a student speaks French.

Given:
- Total number of students = 41
- Number of female students = 19
- Number of male students = 22
- Number of French-speaking female students = 2
- Number of French-speaking male students = 3

We need to determine \( P(M|S) \), the probability that a student is male given that the student speaks French.

First, we calculate the total number of French-speaking students:
\[ 
\text{Number of French-speaking students} = 2 + 3 = 5 
\]

Using the definition of conditional probability:
\[ 
P(M|S) = \frac{P(M \cap S)}{P(S)} 
\]

Where:
- \( P(M \cap S) \) is the probability that a student is male and speaks French.
- \( P(S) \) is the probability that a student speaks French.

Calculate \( P(M \cap S) \):
\[ 
P(M \cap S) = \frac{\text{Number of French-speaking male students}}{\text{Total number of students}} = \frac{3}{41} 
\]

Calculate \( P(S) \):
\[ 
P(S) = \frac{\text{Total number of French-speaking students}}{\text{Total number of students}} = \frac{5}{41} 
\]

Substitute these values into the conditional probability formula:
\[ 
P(M|S) = \frac{\frac{3}{41}}{\frac{5}{41}} = \frac{3}{5} 
\]

Therefore, the probability that a randomly selected student is male, given that the student speaks French, is \( \frac{3}{5} \) or 0.6.
Transcribed Image Text:**Problem Statement: Conditional Probability** Suppose a math class contains 41 students, 19 females (two of whom speak French) and 22 males (three of whom speak French). Compute the probability that a randomly selected student is male, given that the student speaks French. **Solution:** Let: - F denote the event that a student is female. - M denote the event that a student is male. - S denote the event that a student speaks French. Given: - Total number of students = 41 - Number of female students = 19 - Number of male students = 22 - Number of French-speaking female students = 2 - Number of French-speaking male students = 3 We need to determine \( P(M|S) \), the probability that a student is male given that the student speaks French. First, we calculate the total number of French-speaking students: \[ \text{Number of French-speaking students} = 2 + 3 = 5 \] Using the definition of conditional probability: \[ P(M|S) = \frac{P(M \cap S)}{P(S)} \] Where: - \( P(M \cap S) \) is the probability that a student is male and speaks French. - \( P(S) \) is the probability that a student speaks French. Calculate \( P(M \cap S) \): \[ P(M \cap S) = \frac{\text{Number of French-speaking male students}}{\text{Total number of students}} = \frac{3}{41} \] Calculate \( P(S) \): \[ P(S) = \frac{\text{Total number of French-speaking students}}{\text{Total number of students}} = \frac{5}{41} \] Substitute these values into the conditional probability formula: \[ P(M|S) = \frac{\frac{3}{41}}{\frac{5}{41}} = \frac{3}{5} \] Therefore, the probability that a randomly selected student is male, given that the student speaks French, is \( \frac{3}{5} \) or 0.6.
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