The third proportional to 9 and 18 is

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

The mean proportional between 5 and 45 is

1. 10
2. 12
3. 15
4. 25

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 …………… .