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  1. The ratio of the sum to the LCM of two natural numbers is 7 : 12. If their HCF is 4, then the smaller number is :
    1. 20
    2. 16
    3. 12
    4. 8
Correct Option: C

Let the numbers be 4p and 4q where p and q are prime to each other.
LCM = 4pq

( 4p + 4q )
=
7
4pq12

⇒ 12 (p + q) = 7pq
⇒ p = 3, q = 4
∴ Smaller number = 4 × 3 = 12



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