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

Which of the following are in continued proportion?

1. 4, 8, 12
2. 5, 15, 25
3. 6, 36, 216
4. 9, 12, 18

Fill in the blanks :

(i) Ratio has …………… unit.

(ii) To convert a ratio a : b in its simplest form, we divide a and b by …………… of a and b.

(iii) If a : b : : b : c, then a, b, c are said to be in …………… proportion.

(iv) If a, b, c are in continued proportion, then c is called the …………… proportional to a and b.

(v) In a proportion, the first and fourth terms are called the …………… .