To find the fraction of cars that are less than 4 years old and also get at least 60 miles to the gallon, we can use the information given:
- Let \( x \) be the total number of cars in the lot.
- According to the problem, \( \frac{3}{4} \) of the cars are less than 4 years old. Therefore, the number of cars less than 4 years old is \( \frac{3}{4}x \).
- We also know that \( \frac{1}{4} \) of the cars in the lot are both less than 4 years old and get at least 60 miles to the gallon. Thus, the number of cars that are both less than 4 years old and get at least 60 miles to the gallon is \( \frac{1}{4}x \).
Now, to find the fraction of cars that are less than 4 years old and also get 60 miles to the gallon, we need to divide the number of cars that meet both conditions by the number of cars that are less than 4 years old:
\[ \text{Fraction} = \frac{\text{Number of cars less than 4 years old that get 60 mpg}}{\text{Number of cars less than 4 years old}} = \frac{\frac{1}{4}x}{\frac{3}{4}x} \]
The \( x \) cancels out:
\[ \text{Fraction} = \frac{\frac{1}{4}}{\frac{3}{4}} = \frac{1}{4} \cdot \frac{4}{3} = \frac{1}{3} \]
Thus, the fraction of the cars that are less than 4 years old and also get at least 60 miles to the gallon is \(\frac{1}{3}\).
Since none of the answers provided in the responses match \(\frac{1}{3}\), let's check them one by one:
- 3 1/2: This is not a fraction form of cars and doesn’t work.
- 3/16: This is a fraction, but not the right answer.
- 3: This is not a fraction either.
- 4/12: This simplifies to \( \frac{1}{3} \).
The correct choice based on simplification is 4/12, as it is equivalent to \(\frac{1}{3}\).