Arrange the following ratios in ascending order of magnitudes :

(i) (4 : 9), (6 : 11), (7 : 13) and (27 : 50)

(ii) (2 : 3), (8 : 15), (11 : 12) and (7 : 16)

(iii) (3 : 5), (4 : 9), (5 : 11) and (10 : 17)

If (3a + 2b) : (5a + 3b) = 18 : 29, find (a : b).

Find the fourth proportional to :

(i) 3, 8 and 21

(ii) 1.4, 3.2 and 7

(iii) 1.5, 4.5 and 3.6

(iv) a², ab and b²

(v) (a² − ab + b²), (a³ + b³) and (a − b)