Question

Pick out any four numbers from below and arrange them so that they are in proportion 2, 3, 10, 12, 15, 18. 

Ex : 2 : 10 = 3 : 15 

(i) : __________

(ii) : __________

Answer 1

i) 2 : 3; 12 : 18 

a : b = 2 : 3, c : d = 12: 18 

If a, b, C, d are in proportion, then the product of extremes is equal to the product of means.

a . d = b . c 

2 × 18 = 3 × 12 

36 = 36 

So, 2 : 3 = 12 : 18

ii) 10 : 12 = 15 : 18 

a : b = 10 : 12 

c : d = 15 : 18 

If a, b, c, d are in proportion, then the product of extremes is equal to the product of means.

a . d = b . c 

10 × 18 = 15 × 12 

180 = 180 

So, 10 : 12 = 15 : 18

Answer 2

i)  2:12

ii)  3:18