1. Determine the weight of the solute: 3 \text{ grams}
2. Determine the volume of the solvent: 100 \text{ mL}
3. Calculate the weight/volume percent (w/v):
\% \text{(w/v)} = \left( \frac{\text{weight of solute (g)}}{\text{volume of solvent (mL)}} \right) \times 100
\% \text{(w/v)} = \left( \frac{3}{100} \right) \times 100
4. Simplify the calculation:
\% \text{(w/v)} = 3\%
Final answer is 3\%