To find the approximate percent increase in the production of brake pads, we can use the formula for percent increase:
\[ \text{Percent Increase} = \left( \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \right) \times 100% \]
Here, the Old Value is the current production rate of 58 brake pads per hour, and the New Value is the production rate of the new machines, which is 86 brake pads per hour.
Now, substituting the values into the formula:
\[ \text{Percent Increase} = \left( \frac{86 - 58}{58} \right) \times 100% \]
Calculating the difference:
\[ 86 - 58 = 28 \]
Now substituting back into the formula:
\[ \text{Percent Increase} = \left( \frac{28}{58} \right) \times 100% \]
Calculating \( \frac{28}{58} \):
\[ \frac{28}{58} \approx 0.48276 \]
Now, multiplying by 100 to get the percentage:
\[ 0.48276 \times 100 \approx 48.28% \]
Rounding this to the nearest whole number gives approximately 48%. Therefore, the approximate percent increase in the production of brake pads at the factory is:
A. 48%