Let the cost price be C, the marked price be M, and the selling price be S. The ratio of the marked price to the cost price is:
\[ M : C = 3 : 2 \]
So, we can express M in terms of C:
\[ M = \frac{3}{2}C \]
The profit is 20%, so the selling price is:
\[ S = C + 0.2C = 1.2C \]
The ratio of marked price to selling price is:
\[ \frac{M}{S} = \frac{\frac{3}{2}C}{1.2C} \]
\[ = \frac{3}{2} \times \frac{1}{1.2} \]
\[ = \frac{3}{2.4} = \frac{5}{4} \]
The ratio of the marked price to the selling price is 5:4.