Final answer:
After calculating a 6% decrease on the increased stock price of $91.70, the final stock price is $86.20, which is a reasonable figure for such a change.
Step-by-step explanation:
Luis bought stock at $78.90. The next day, the price increased by $12.80, making the new stock price $91.70. This price then changed by -6%. To find the final stock price, you first calculate 6% of $91.70:
6% of $91.70 = 0.06 × 91.70 = $5.502
This amount ($5.502) represents the decrease in the stock price, since the change is negative. Therefore, you subtract it from the stock's increased price of $91.70 to determine the final stock price:
Final stock price = $91.70 - $5.502 = $86.198
Rounded to the nearest cent, the final stock price is $86.20. This answer seems reasonable as a -6% change would slightly reduce the increased stock price.