In the mid 1990s selected automobiles had an average cost of $12000.The average cost of those same automobiles is now $20000. What was the rate of increase for these automobiles between the two time periods?

20,000 - 12,000 = 8,000

8,000 / 12,000 = = 0.666667 = 67%

To calculate the rate of increase for the automobiles between the two time periods, you can use the formula:

Rate of Increase = (New Value - Old Value) / Old Value

In this case, the old value is $12000 and the new value is $20000. Plugging these values into the formula, we get:

Rate of Increase = ($20000 - $12000) / $12000

Simplifying the equation:

Rate of Increase = $8000 / $12000

Dividing the numerator by the denominator:

Rate of Increase = 0.6667

Multiplying by 100 to get the percentage:

Rate of Increase = 66.67%

So, the rate of increase for these automobiles between the mid 1990s and now is approximately 66.67%.