In a factory that manufactures light bulbs, 0.04% of all light bulbs manufactured are defective. On the average, there will be three defectve light bulbs out of how many manufactured?

Options

A. `2,500`
B. `5,000`
C. `7,500`
D. `10,000`

Answer

To solve the problem, we need to find out how many light bulbs are manufactured if 0.04% of them are defective, and on average, there are 3 defective light bulbs.

### Step-by-Step Solution:

1. **Understand the Problem Statement**: We know that 0.04% of all manufactured light bulbs are defective. We need to find the total number of light bulbs (let's denote this as \( X \)) if there are 3 defective bulbs on average.

2. **Set Up the Equation**: Since 0.04% of the total light bulbs \( X \) are defective, we can express this mathematically:
\[ \text{Defective bulbs} = 0.04\% \times X \]
We can convert 0.04% to a decimal:
\[ 0.04\% = \frac{0.04}{100} = 0.0004 \]
Therefore, the equation becomes:
\[ 0.0004 \times X = 3 \]

3. **Solve for \( X \)**: To find \( X \), we need to isolate it in the equation:
\[ X = \frac{3}{0.0004} \]

4. **Calculate \( X \)**: Performing the division:
\[ X = \frac{3}{0.0004} = 3 \div 0.0004 = 7500 \]

5. **Conclusion**: The total number of light bulbs manufactured is \( 7500 \).

### Final Answer:
The average number of light bulbs manufactured is **7500**.