problem: If a drip of water is equivalent to $\frac{1}{4}$ of a milliliter, how many drips are in a liter of water? Note: 1 liter = 1000 milliliters.
solution: If a drip of water is equivalent to $\frac{1}{4}$ of a milliliter, then $4$ drips of water must be equivalent to $1$ milliliter of water. Since there are $1000$ milliliters in a liter, it follows that there are $4 \times 1000 = \boxed{4000}$ drips in a liter of water.