A ratio between two numbers is 3 : 4 and their L.C.M. is 180. The first number is Choose the correct choice from the following:
A) 60
B) 45
C) 20
D) 15
E) None
Sol.   Let the required numbers be 3x and 4x. Then, their L.C.M. is 12x.   ∴ 12x = 180⇔ x = 15. Hence, the first number is 45.   Answer 45
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A ratio between two numbers is 3 : 4 and their L.C.M. is 180. The first number is