1. Use colligative property formulas

For a non-electrolyte like glucose, van't Hoff factor $i=1$.

So, $\Delta T_b = K_b m$ $\Delta T_f = K_f m$

2. From the boiling point data

Given:

• Molality $m = 1.5$
• Elevation in boiling point $\Delta T_b = 4\,\text{K}$

Thus, $K_b = \frac{\Delta T_b}{m} = \frac{4}{1.5}$

3. From the freezing point data

Given:

• Molality $m = 4.5$
• Depression in freezing point $\Delta T_f = 4\,\text{K}$

Thus, $K_f = \frac{\Delta T_f}{m} = \frac{4}{4.5}$

4. Find the ratio

$\frac{K_b}{K_f} = \frac{\frac{4}{1.5}}{\frac{4}{4.5}}$

Cancel $4$: $\frac{K_b}{K_f} = \frac{4.5}{1.5} = 3$

5. Final answer

$\boxed{3}$

The derived answer matches the stored correct answer.