1.  Out of the ratio 7 : 15, 15 : 23, 17 : 25 and 21 : 29 the smallest one is ?
A. 17 : 25
B. 7 : 15
C. 15 : 23
D. 21 : 29

Answer: Option B

Explanation:

7 : 5 = 7/15 = 0.466
15 : 23 = 15/23 = 0.652
17 : 25 = 17/25 = 0.68
and 21 : 29 = 0.724
∴ The smallest one is 7 : 15.