Question

Which one of the following ratios is proportional to 3:5?

• A. 9:15
• B. 3:17
• C. 1:9
• D. 6:12

Answer 1

The correct option is A 9:15

Two ratios are proportional when they are equal.
Writing all the options in simplest form,

(a) 9:15 = $\frac{3\times 3}{3\times 5}=\frac{3}{5}$ = 3:5

(b) 3:17 is in its simplest form because there are no common factors between the antecedent and the consequent except 1.

(c) 1:9 is in its simplest form because there are no common factors between the antecedent and the consequent except 1.

(d) 6:12 = $\frac{1\times 6}{2\times 6}=\frac{1}{2}$ = 1:2

Clearly, 9:15 is proportional to 3:5.