Question

If a ∶ b = 2 ∶ 3, b ∶ c = 5 ∶ 7 and c ∶ d = 4 ∶ 5. Then find a ∶ b ∶ c ∶ d.  
1. 40 ∶ 60 ∶ 84 ∶ 105
2. 44 ∶ 60 ∶ 84 ∶ 105
3. 40 ∶ 60 ∶ 84 ∶ 107
4. 40 ∶ 64 ∶ 84 ∶ 105

Answer 1

Correct Answer - Option 1 : 40 ∶ 60 ∶ 84 ∶ 105

Given:

a ∶ b = 2 ∶ 3

b ∶ c = 5 ∶ 7 

c ∶ d = 4 ∶ 5

Calculation:

a ∶ b ∶ c ∶ d

2 ∶ 3 ∶ 3 ∶ 3

5 ∶ 5 ∶ 7 ∶ 7

4 ∶ 4 ∶ 4 ∶ 5

⇒ (2 × 5 × 4) ∶ (3 × 5 × 4) ∶ (3 × 7 × 4) ∶(3 × 7 × 5)

⇒ 40 ∶ 60 ∶ 84 ∶ 105

∴ a ∶ b ∶ c ∶ d = 40 ∶ 60 ∶ 84 ∶ 105

The correct option is 1 i.e. 40 ∶ 60 ∶ 84 ∶ 105