The probability of selecting a girl from a class is `3/8` and there are total 360 students in the class. Find the number of boys in the class.

Options

A. 225
B. 135
C. 215
D. 240

Answer

To solve the problem, we need to find the number of boys in the class given the probability of selecting a girl and the total number of students.

### Step-by-Step Solution:

1. **Understanding the Probability**:
The probability of selecting a girl from the class is given as \( \frac{3}{8} \). This means that out of every 8 students, 3 are girls.

2. **Finding the Total Number of Girls**:
To find the number of girls in the class, we can use the formula for probability:
\[ P(\text{girl}) = \frac{\text{Number of girls}}{\text{Total number of students}} \]
Here, we know that:
\[ P(\text{girl}) = \frac{3}{8} \quad \text{and} \quad \text{Total number of students} = 360 \]
Let \( G \) be the number of girls. Therefore, we can set up the equation:
\[ \frac{G}{360} = \frac{3}{8} \]

3. **Cross-Multiplying to Solve for G**:
Cross-multiplying gives us:
\[ 8G = 3 \times 360 \]
Calculating the right side:
\[ 3 \times 360 = 1080 \]
Thus, we have:
\[ 8G = 1080 \]

4. **Dividing to Find G**:
Now, divide both sides by 8 to find \( G \):
\[ G = \frac{1080}{8} = 135 \]
So, there are 135 girls in the class.

5. **Finding the Number of Boys**:
The total number of students is 360. To find the number of boys \( B \), we subtract the number of girls from the total:
\[ B = \text{Total students} - \text{Number of girls} \]
Substituting the values we have:
\[ B = 360 - 135 = 225 \]

### Final Answer:
The number of boys in the class is **225**.