If $W_1$ is the initial mass of raisins and $W_2$ is the final mass after soaking in water, then the percentage of water absorbed by the raisins is

The initial mass of the dry raisins is $W_1$. After soaking in water, the raisins absorb water via endosmosis, and their final mass becomes $W_2$. The mass of water absorbed by the raisins is the difference between the final and initial mass, which is $(W_2 - W_1)$. To find the percentage of water absorbed, this mass of absorbed water is divided by the initial dry mass ($W_1$) and multiplied by 100. Therefore, the formula is $\frac{W_2 - W_1}{W_1} \times 100$.

• Option A is incorrect because it subtracts the final mass from the initial mass, which would yield a negative value since $W_2 > W_1$.
• Option B is incorrect because it calculates the percentage absorption relative to the final wet mass ($W_2$) instead of the initial dry mass ($W_1$).
• Option D is incorrect because it combines both errors: it subtracts the final mass from the initial mass and divides by the final mass.