To calculate the percent increase over the 8-month period, you can use the formula:
\[ \text{Percent Increase} = \left( \frac{\text{New Price} - \text{Old Price}}{\text{Old Price}} \right) \times 100 \]
Here, the old price is 28.40 and the new price is 52.90.
- Calculate the difference in prices:
\[ \text{Difference} = 52.90 - 28.40 = 24.50 \]
- Calculate the percent increase:
\[ \text{Percent Increase} = \left( \frac{24.50}{28.40} \right) \times 100 \]
\[ \text{Percent Increase} = \left( 0.86338 \right) \times 100 \approx 86.34% \]
The closest answer from the given options is 86.27%.