Correct Answer - Option 1 : 4
Given:
The ratio of three numbers = 3 ∶ 5 ∶ 7
LCM = 420
Calculation:
Let the number be 3x, 5x and 7x.
LCM of (3x, 5x and 7x) = 3 × 5 × 7 × (x)
LCM of (3x, 5x and 7x) = 105x
According to the question,
105x = 420
⇒ x = 4
HCF of (3x, 5x, and 7x) = x = 4
Here, x is the common factor of three numbers.
∴ The HCF of the three numbers is 4.