Question

Write true or false for each of the following.

a) 13 : 12 :: 12 : 13 

b) 5 : 6 :: 7 : 8

Answer 1

a) 13 : 12 :: 12 : 13 

Given proportion is 13 : 12 :: 12 : 13 

If a, b, c, d are in proportion, then a.d = b.c 

13 × 13 = 12 × 12 

169 ≠ 144 

So, the given proportion is false.

b) 5 : 6 :: 7 : 8 

Given proportion is 5 : 6 :: 7 : 8 

If a, b, c, d are in proportion, then a.d = b.c 

5 × 8 = 6 × 7 

40 ≠ 42 

So, the given proportion is false.