The ratio $\dfrac{1}{8} : \dfrac{1}{12}$ converted to the simplest form is

1. 12 : 8
2. 3 : 2
3. 2 : 5
4. 8 : 20

If A : B = 2 : 5 and B : C = 4 : 5, then C : A = ?

1. 5 : 2
2. 2 : 1
3. 15 : 8
4. 25 : 8

If 12 : x : : 15 : 25, then the value of x is

1. 10
2. 15
3. 18
4. 20

The third proportional to 9 and 18 is

1. 21
2. 24
3. 27
4. 36