Question

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Explanation:

Step1: Define the problem

We need to find how many rocks of length $\frac{1}{4}$ meter are needed to fill a pit of length 1 meter. This is a division problem where we divide the total length of the pit by the length of each rock.

Step2: Set up the division

The formula to find the number of rocks $n$ is $n=\frac{\text{Length of pit}}{\text{Length of each rock}}$. Substituting the values, we get $n = \frac{1}{\frac{1}{4}}$.

Step3: Solve the division

Dividing by a fraction is the same as multiplying by its reciprocal, so $\frac{1}{\frac{1}{4}}=1\times4 = 4$.

Answer:

4 rocks (corresponding to the option "4 rocks")