Final answer:
The price of the car increased by 400% over the forty-year period from $6,000 to $30,000.
Step-by-step explanation:
To calculate the percentage increase of the price of a car over forty years, you use the formula:
Percentage Increase = [(Final Price - Initial Price) / Initial Price] × 100
In this case, the Initial Price is $6,000 and the Final Price after forty years is $30,000. Plugging in these values gives:
Percentage Increase = [($30,000 - $6,000) / $6,000] × 100
Percentage Increase = [$24,000 / $6,000] × 100
Percentage Increase = 4 × 100
Percentage Increase = 400%
So, the price of the car increased by 400% over the forty-year period.